| Paper | Title | Page |
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| TUPMP001 | Design and Experimental Results of a 1.1kA/800V AC Power Supply for Sirius Booster Dipoles | 1227 |
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| Sirius is a 4th generation synchrotron light source de-signed and being built by Brazilian Synchrotron Light Laboratory (LNLS), with first beam scheduled for 2019. Approximately thousand power supplies (PS) will be needed to feed all the magnets, being 57 to operate the booster injector. The two booster dipole PS are the most complex, not only due to their higher current (1.1 kA), voltage (800 V) and power (333 kW) output, but also because the current must follow a quasi-triangular waveform, from a value close to zero to almost the maximum in 320 ms and at a repetition rate of 2 Hz. Due to the high output values, each PS is formed by two sets in parallel of 4 modules in series, what means 8 modules with 550 A / 200 V output. In order to reduce the 2-Hz effect in the grid, each module has two main stages. The input stage has the function to regulate the average voltage in a capacitor bank consuming a constant RMS current from the grid, which value depends on of the PS average output power. The output stage has the function to transfer the energy from the capacitor bank to the load, with the output cur-rent following the reference waveform. This work describes this PS, showing its topology, some aspects of its design and obtained results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP001 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP002 | Overview of Sirius Power Supply System | 1230 |
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| Sirius is a 4th generation synchrotron light source designed and under construction by Brazilian Syn-chrotron Light Laboratory (LNLS), which first beam is scheduled to operate in 2019. Almost a thousand Pow-er supplies (PS) will be needed to feed all magnets of the magnetic lattice, with outputs ranging from 10A to 1.1kA and 50W to 333kW. Almost all power supplies were designed at LNLS. Only three families of power modules were de-signed: low power (FBP), high power (FAP) and AC (FAC). Each PS can have up to 8 modules in a parallel or/and series association, in order to reach the rated output values. All PS are digitally controlled by the same hardware and firmware, also developed by LNLS, called Digital Regulation System (DRS), but with different parameter settings. The DRS is also responsible by the communi-cation with other systems, PS monitoring, data man-agement, etc. This work presents an overview of this system, showing the PS specifications, family topologies and results of tests. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP002 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP003 | Development of Remote Handleable Axially Decoupled Radiation Resistant Vacuum Seal | 1233 |
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Funding: ARIEL is funded by the Canada Foundation for Innovation (CFI), the Provinces of AB, BC, MA, ON, QC, and TRIUMF. TRIUMF receives federal funding via a contribution agreement with the NRC of Canada. Advanced Rare IsotopE Laboratory (ARIEL) facility is a major expansion of TRIUMF’s rare isotope research program. Aiming to triple the production of rare isotopes, ARIEL facility includes the new electron linac driver and two target stations for electron and proton beams. Particularities of ARIEL target stations design define the requirements for vacuum interfaces with both primary electron and proton beamlines and rare-isotope beamlines. None of the existing products fully met the requirements, driving the development of custom vacuum interfaces. The design of new vacuum seals is driven both by unique design specifications (limited amount of allowed axial forces, extreme radiation resistance, remote handleability and high repeatability) as well as limitations of the proposed design of beamline infrastructure in the target hall (limited available space and the choice of materials for certain components). This paper discusses preliminary results of the vacuum seal development and presents first results of prototype testing. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP003 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP004 | Dynamic Pressure in the LHC - Influence of Ions Induced by Ionization of Residual Gas by Both the Proton Beam and the Electron Cloud | 1236 |
| SUSPFO006 | use link to see paper's listing under its alternate paper code | |
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Funding: work supported by FCC project (CERN & LAL-CNRS-IN2P3) Ultra-High Vacuum is an essential requirement to reach design performances in high-energy particle colliders. For the future HL-LHC or FCC study, the understanding of the beam interactions with the vacuum chamber is fundamental to provide solutions to mitigate the pressure rises induced by electronic, photonic and ionic molecular desorption. Studies were performed on the ions, produced by molecular ionization generated by the proton beam and the electron cloud, and stimulating molecular desorption by the surface bombardment. In-situ measurements were carried out, on the LHC Vacuum Pilot Sector (VPS)*, to monitor the dynamic pressure, and to collect the electrical signals due to the electron cloud and to the ions interacting with the vacuum chamber walls. Experimental measurements of electrical signals recorded by copper electrodes were compared to calculations taking into account both the Secondary Electron Yield of copper and electron energy distribution. Finally, it seems that copper electrodes were not fully conditioned and an ion current could be estimated. * THE LHC VACUUM PILOT-SECTOR PROJECT B. Henrist, V. Baglin, G. Bregliozzi, and P. Chiggiato, CERN, Geneva, Switzerland Proceedings of IPAC2014, Dresden, Germany. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP004 | |
| About • | paper received ※ 01 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP006 | Cryogenic Tests of the SPIRAL2 LINAC Systems | 1240 |
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| Two full cool-down of the SPIRAL2 superconducting LINAC have been performed in 2017 and 2018 respectively, followed by a total of around 5 months of tests at 4 K. Several cool-down strategies were tested, in order to minimize 100 K effect on the SC cavities. Helium bath regulations (level and pressure) have been tested and optimized. Effects of pressure instabilities and coupling with the cryogenic plant have also been observed. Cryogenic performances of each cryomodule have been measured. Low-level RF measurements were also performed on all cavities and showed unidentified modulations at frequencies around 5Hz. These turned out to be thermoacoustic oscillations (TAO) on the cryogenic lines, which generate important pressure instabilities. Several solutions to remove TAO and cure these instabilities have been tested and one has been successfully deployed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP006 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP007 | DYVACS (DYnamic VACuum Simulation) Code: Calculation of Gas Density Profiles in Presence of Electron Cloud | 1244 |
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The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 (and then PyVASCO**) is already used to estimate vacuum stability and density profiles in steady state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds. Therefore, we propose an upgrade of this code by introducing electron cloud maps*** to estimate the electron density and the ionization of gas by electrons, leading to an increase of both electron- and ion-induced desorption. Results obtained with the new code (called DYVACS for DYnamic VACuum Simulation) will be compared to pressure measurements in the VPS sector**** of the LHC.
* A. Rossi, Tech. Rep., LHC Proj. Note 341 ** I. Aichinger, et al arXiv:1707.07525 *** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007) **** B. Henrist et al, Proc. IPAC2014, Dresden |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP007 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP011 | Storageless Resonant Converter for Accelerator Magnets | 1248 |
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| Elettra Sincrotrone Trieste, a specialized research centre generating high quality synchrotron radiation, has been in operation since 1993 and was revised in 2009. Recently, Elettra has been funded for a complete renewal of the storage ring. For the new machine, it is planned to employ state of the art converters, mostly of which will be designed in-house. For this purpose, it has been decided to evaluate the performance of a storage-less resonant converter, pro-posed by Dr. Slobodan Ćuk, which is a step down DC/DC converter consisting of four switches, one resonant capac-itor and two resonant inductors. For this purpose, the voltage conversion ratio of the converter has been de-rived. The topology was confirmed with simulation and a PCB layout has been designed, which is still to be tested. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP011 | |
| About • | paper received ※ 08 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP012 | Power Converters for the ESS Warm Magnets: Procurement Status | 1251 |
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| In the frame of the Italian In-Kind collaboration for the construction of the European Spallation Source (ESS), Elettra Sincrotrone Trieste research center is in charge, among all, of the provision of the power converters for the warm magnets of the superconducting part of the linear accelerator and of the proton beam transport line. The procurement process is running for all types of power converters. The first components have been delivered to ESS already in March 2018, while the Dipole and Quadrupole power converters are under construction. The first batches have been factory tested and shipped to Lund. The corrector power converters have been manufactured and are currently tested and calibrated at Elettra before their delivery to ESS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP012 | |
| About • | paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP013 | New Design of Vacuum Chambers for Radiation Shield Installation at Beam Injection Area of J-PARC RCS | 1255 |
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| One of the issues in the J-PARC 3 GeV rapid cycling synchrotron is the high residual radiation dose around the beam injection point. A radiation shield is necessary to reduce radiation exposure of workers when maintenance is performed there. A space to install the radiation shield should be secured by newly designing a structure of the vacuum chamber at the injection point and the alumina ceramics beam pipes for the shift bump magnets. To make the space for the shield, the chamber is lengthened along the beam line and the cross-sectional shape is changed from circle to rectangle. The displacement and inner stress of the vacuum chamber due to atmospheric pressure was evaluated to be enough small by the calculation. For the ceramics beam pipe’s rf-shield, the damping resistor was effective to reduce the induced modulation voltages by the pulsed magnetic field. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP013 | |
| About • | paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP014 | Digital Control System of High Precision Magnet Power Supply for SPring-8-II | 1259 |
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| For the SPring-8 upgrade plan, SPring-8-II, a variety of magnet power supplies (PS) from 10 W to larger than 100 kW with a high current stability of about 10 ppm (pk-pk, typ.) are required. In order to develop the PSs within a given time and budget, we plan to use a common control system based on a digital control technology that can be adopted for the variety and the high precision PSs. The system consists of a high-precision analog-digital converter (ADC) circuit and a field programmable gate array (FPGA). Since the precision of the ADC circuit determines the current stability of the PS, we first developed the ADC circuit of high accuracy of less than 10 ppm (pk-pk). A proportional-integral (PI) control logic and a digital pulse width modulation (PWM) function was implemented in the FPGA firmware. These functions can be easily modified for each power supply by a desktop computer. We prototyped a DC power supply equipped with the newly developed digital feedback control system and confirmed that the current fluctuation was suppressed to less than 10 ppm (pk-pk). In the presentation, we will report the current status and future perspective of our power supply development including the evaluation results of the new circuits and the power supply we have developed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP014 | |
| About • | paper received ※ 16 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP015 | Magnet Power Supply Calibration with a Portable Current Measuring Unit at the J-PARC Main Ring | 1263 |
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| In the J-PARC MR, 96 bending magnets (BMs) are used in total. They are divided into 6 groups of 16 BMs. The 16 BMs in each group are connected in series and driven by a single power supply. Since all 96 BMs are symmetrically located in the ring, the magnet currents regulated by the 6 power supplies need to be same. Each power supply performs output current feedback control using electronic circuits including analog amplifications and AD / DA conversions. Due to individual differences of the electronic circuits, output current is generally expected to be different for each power supply. Therefore, we developed a current measurement unit with the portable DCCT as an independent reference. Further, we measured the magnet currents regulated by the 6 BM power supplies using the unit. We report the details of the unit as well as the results of the current measurements. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP015 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP016 | New Power Supply of Main Magnets for J-Parc Main Ring Upgrade | 1266 |
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| It is plans that the proton beam power provided to experimental facilities increase with shortening repetition period in J-PARC Main Ring (MR). As the shorten repetition period, the replacement of the power converters for main magnets in J-PARC MR is necessary to cope with issues such as power fluctuation of the main grid and increase of the output voltage. We have considered and developed the power converters with a 10 MW class which have the capacitor banks with the large capacitance. In the end of 2017, the first new power converter for a bending magnets family, which is the largest power converter in this upgrade plan, was installed in J-PARC site and the power test is ongoing using a dummy and a real load. In this report, the first new power converter for a bending magnets family in J-PARC MR is reported including the test results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP016 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP017 | Design of Scanning Magnet Power Supply for HUST-PTF | 1269 |
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| An active scanning proton therapy facility is being de-veloped at Huazhong University of Science and Technol-ogy（HUST）. By controlling the deflection position of the beam with scanning magnets at different times, the superposition of discrete spot beams will form a specified shape and dose distribution conformal to the target tu-mour. A high precision and fast response power supply is required to deflect the beam quickly and accurately. In this paper, the TOSCA module in Opera3D is used to model and simulate the scanning magnets and to obtain the equivalent inductance of the magnet. Then the calcu-lated equivalent resistance inductance instead of the magnet is used to design the scanning magnet power supply. A high-voltage bridge is utilized to achieve fast response speed, and a low voltage bridge and PI control algorithm is adopted to ensure power supply accuracy. The Simulation result shows that the designed power supply meets the requirements of response speed and accuracy. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP017 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP018 | Feasibility Tests of a Vacuum System for SPring-8-II | 1272 |
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| For SPring-8-II, the major upgrade of SPring-8, a test half-cell including permanent/electro magnets and a vacuum system was constructed, and hardware feasibility tests have been performed since 2017. Features of the SPring-8-II vacuum system are 1) introduction of the concept of a stainless steel 12 m-long integral chamber (LIC) with a welded structure, and 2) adoption of ex-situ baking of the chamber. The 12 m LIC with a narrow aperture, flangeless structure and a minimum number of bellows was designed so that the vacuum system could be installed without interference with the magnets of a narrow bore diameter aligned on girders with a severe packing factor. For replacement of the existing system with a new one in a short black-out period, the 12 m LIC is planned to be moved into the accelerator tunnel with keeping ultra-high vacuum (UHV) by closing thin gate valves at both ends, after evacuation to UHV by ex-situ baking and NEG activation. This presentation will overview the vacuum system, mainly the 12 m LIC, developed for the test half-cell, and describe the vacuum performance and the result of the assembly test conducted with the permanent/electro magnets. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP018 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP019 | Vacuum Performance of the NEG-coated Chamber for U#19 at PF-ring | 1276 |
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| At the Photon Factory storage ring (PF-ring) in KEK, a new APPLE-II type elliptically polarizing undulator (U#19) was installed in October 2018. The U#19 vacuum chamber is 4.1 meters in length, and the beam channel with a 15x90 elliptical profile and two cooling-water channels alongside were formed by extrusion of A6060-T6 aluminum alloy. The inner surface of the beam channel is coated with a Ti-Zr-V Non-Evaporable Getter (NEG) thin film, as it has a high effective pumping speed and a low Photon Stimulated Desorption (PSD) yield. After the installation of the U#19, the neighboring uncoated chambers and vacuum components were baked out at 200 °C for 44 hours, and then the NEG coating was activated at 160 °C for 48 hours. As a result, the pressures in the neighboring chambers reached as low as 10-8 Pa. The conditioning of the vacuum chambers with irradiation of Synchrotron radiation evolved favorably as had been expected by a combined simulation of Synrad and Molflow, leading to a satisfactory recovery of the beam lifetime. Vacuum performance of the NEG-coated chamber was assessed especially by means of a residual gas analysis, and the properties of the NEG film were characterized by surface analyses including SEM, EDX, and XRD. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP019 | |
| About • | paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP020 | The Research on the Calibration of Direct-Current Current Transformers | 1280 |
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| The measurement accuracy of direct current-current transformer (DCCT) is one of the key factors influencing the output of high-precision direct current power supply. In this paper, a calibration system designed by measuring resistance principle with a high accuracy direct current comparator (DCC) was presented for DCCT whose measurement accuracy is better than 10-5. The system can achieve high-precision calibration of DCCT within the measurement range of 0-400 A, and the uncertainty of the system calibration is better than 1.1×10-6 in the whole range. The accuracy and linearity of DCCT are tested to verify the accuracy of the whole calibration system, thereby the current accuracy of the magnet power supply can be further improved. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP020 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP021 | Comparison of TiZrV Non-evaporable Getter Films Deposited by DC Magnetron Sputtering or Quantitative Deposition | 1283 |
| SUSPFO057 | use link to see paper's listing under its alternate paper code | |
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| Ti-Zr-V non-evaporable getter (NEG) films have been widely used in vacuum chambers of various accelerators since their discovery. Recently, we have used a new method called ’quantitative deposition’ to deposit Ti-Zr-V NEG films on nichrome substrates. The surface morphology and surface chemical bonding information were collected by scanning electron microscopy. Although the film deposited by DC magnetron sputtering has more uniform grain growth, smoother grain boundaries and higher porosity, the two films all have porous network structure and can be used as getter films. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP021 | |
| About • | paper received ※ 24 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP022 | Research on Digital Scanning Power Supply Technology for Proton Therapy System | 1286 |
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Funding: Work supported by The National Key Research and Development Program of China, with grant No. 11505068 Proton has great advantages in the field of cancer radiotherapy because of its good characteristic of Bragg peak. HUST-PTF is a proton therapy facility under development in Huazhong University of science and technology. It delivers the beam to the patients with a pencil beam scanning nozzle. Scanning power supplies are placed in the nozzle of the proton therapy device and they are required high accuracy, high speed and high stability. In this paper，the structure diagram of HUST-PTF is shown. The parameters of scanning magnets and its power supply are introduced. Finally, some test results of power supply are shown. The next work will debug the control system of the scanning power supply and adjust it with the scanning magnet to see if it meets the design requirements. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP022 | |
| About • | paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP023 | Design of Digital Controller for Multi Module Series-parallel Accelerator Power Supply | 1288 |
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Funding: Supported by funds, Key laboratory of particle Acceleration Physics & Technology, Institute of High Energy Physics, Chinese Academy of Sciences，Project number：Y5294107TD With the development of accelerators, Accelerator physics require power supply output high voltage and current (Peak power reached MWs). And the current stability requirements better than 10ppm. Therefore, the power supply is mostly used in the mode of module series-parallel. However, during actual commissioning, the power supply often does not run at rated current. If the power supply is running at less than 30% of the rated current, the power output current stability will drop sharply. This topic designed a set of digital controller for multi-module serial-parallel control. The digital controller can automatically adjust the number of input modules according to the current setting, and can automatically allocate the required PWM number of the module. While taking into account the synchronization between the various modules, Ensure the power supply is always running at an optimal working condition. Through a special AD conversion hardware design and advanced closed-loop controller algorithm, the digital controller can provide up to 20 high-resolution PWM signals to drive power conversion devices. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP023 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP024 | Research on Module Design and Network Management of Accelerator Power Supply System | 1291 |
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| Accelerator power supply system is a very special system. Many factors such as high number of power supplies, uninterrupted operation and unreasonable design lead to high failure rate, long maintenance time and the discovery of the fault is not timely, which bring a lot of unnecessary troubles to the operator. In this paper, a networked control method for accelerator power supply is studied, and the power supply parallel connection technology is used to maximize the trouble-free time of the power supply and increase the redundancy performance of the power supply. With independent networked control, the accelerator power supply system becomes a whole, no longer relying solely on the control of the accelerator control system, but in a network system with self-diagnosis and self-healing. Through the monitoring and management of the upper computer, the power supply system will be work stable, and the function of remote operation and remote repair of the power supply is realized finally. This is a research direction for the operation of large accelerator power supply systems in the future. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP024 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP025 | Design of Fast Corrector Magnet Power Supply for HEPS | 1294 |
| SUSPFO065 | use link to see paper's listing under its alternate paper code | |
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| High energy photon source is a fourth-generation synchrotron radiation light source with energy of 6Gev and ultra-low emittance (<0.1nm’rad). The ultra-low beam emittance requires high beam stability. Therefore, we develop a fast correction power supply with high bandwidth and low current ripple to improve the performance of the fast close orbit correction sys-tem to prove the high beam stability. The power supply adopts FPGA for full-digital control and use high speed ADC with temperature control. The power sup-ply has a small signal-bandwidth of 10 kHz and output current ripple lower than 20ppm. In this paper, we will describe the hardware design and software control methods and the test results will be demonstrated | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP025 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP027 | Research and Design of Digital Magnet Power Supply Controller | 1297 |
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Funding: Supported by’the Fundamental Research Funds for the Central Universities’（WK2310000064） Hefei Advanced Light Source (HALS) is the fourth-generation radiation light source in China which is under design. Ultra-low beam emittance requires higher performance of power supply system. The power supply controller is a key part of the power system. This article describes the design and testing of high-stability power controllers and fast corrector power supply controllers. A new controller architecture is proposed for the problems of the two controllers. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP027 | |
| About • | paper received ※ 29 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP028 | Research Progress of Power Supply System in HALS | 1300 |
| SUSPFO068 | use link to see paper's listing under its alternate paper code | |
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Funding: Supported by ’the Fundamental Research Funds for the Central Universities’（WK2310000064） Supported by the Hefei Advanced Light Source Pre-research Project. Hefei Advanced Light Source (HALS) is the fourth generation light source in China’s planning and construction. In order to achieve the diffraction limit of the emission and improve the beam quality, the research on magnet power supply (MPS) technology is essential. We have designed a variety of solutions for different power supplies. We designed the first version of the high stability power supply control card. The first version of the high-stability power supply control card was designed and tested with a small power module. Our pre-research system has developed a corrector magnet power supply with a small signal response bandwidth higher than 10 kHz. The developed power prototypes all use self-developed controllers, and most of the test results can meet the requirements. This article describes the progress of the HALS power supply system. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP028 | |
| About • | paper received ※ 08 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP029 | Establishing a Laser Treatment to Suppress the Secondary Electron Emission | 1303 |
| SUSPFO071 | use link to see paper's listing under its alternate paper code | |
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| Laser treatment has a significant inluent on suppressing the secondary electron emission(SEE). The new synchrotron radiation light source, the Hefei Advanced Light Source(HALS) has a strict requirement on the SEE. In this paper, we used a 355nm laser to process copper sample. After the laser treatment, the secondary electron yield(SEY) reduced from 2.05 to 0.86. We used the scanning electron microscope(SEM) to analysis the surface of sample after the laser treatment. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP029 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP031 | Research on Secondary Electron Emission Characteristics of Diamond-like Carbon Thin Films | 1306 |
| SUSPFO081 | use link to see paper's listing under its alternate paper code | |
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| In modern particle accelerators, the build-up of electron cloud is a main limiting factor for the achievement of high-quality beam. Among the techniques to mitigate it, coating the internal walls of the beam pipes with a thin film which has a low secondary electron yield (SEY) is considered to be one of the most effective means. From several earlier studies, it was found that diamond-like carbon (DLC) thin films are potential coatings. This paper is mainly about the research on secondary electron emission characteristics of DLC thin films. The secondary electron emission (SEE) tests were done at temperature of 298 K and vacuum pressure of 2×10-9 Torr. Here, we obtained the characteristics of the SEE from DLC film coatings with different thickness under ultrahigh-vacuum (UHV) conditions. The maximum secondary electron yield (SEY), δmax, of the DLC thin films under different primary electron doses were also obtained, respectively. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP031 | |
| About • | paper received ※ 26 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP032 | Design of Analog to Digital Converter Scheme for High - Precision Electromagnet Power supply | 1309 |
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| This paper deals with the design of an analogue-to-digital converter (ADC) scheme for a highly precise magnet current supply (MPS). The MPSs are requires with stable and precise current specification in range of the ppm. To meet the requirements, the AD circuit is composed of parallel ADCs of low-medium resolution. Digitally, the oversampling and averaging are performed to increase both the effective resolution and the signal to noise ratio (SNR). The implemented AD circuit was improved about 18 dB (32 times oversampling). The MPS applied by the proposed ADC scheme provides more precise control and the stable current within 10 ppm at 200 A. The experiment used a dipole magnet of the PAL-XFEL and its results proved feasibility through precisely measurable DVM3458A (Keysight Co.). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP032 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP033 | Design of the Neutron Imaging Differential Pumping Line at LLNL | 1312 |
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Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The neutron imaging system at LLNL is a radiographic capability for imaging objects with fast, quasi-monoenergetic neutrons at ≤1mm spatial resolution. The neutron production source is a deuteron beam (4 or 7 MeV) incident upon a rotating, high-pressure, windowless, pure-deuterium gas target. The windowless nature of the target combined with the high pressure leads to significant gas leakage upstream of the neutron production target. This leakage degrades the imaging quality by (1) increasing the depth-of-field blurring and (2) increasing the beam diameter and divergence in the transverse direction via angular straggling in the residual gas. To mitigate these effects, and guided by bench tests and simulations, we designed a differential pumping line (DPL) to ensure the highest quality imaging system. The system consists of three primary stages (chambers), each separated by carefully shaped apertures. These apertures can be long and thin with low-angle tapers due to the high quality of the beam optics (convergence at the target < 5mrad) and low emittance of the beam (~5 pi mm-mrad). The primary cascaded roots pumps are sized to remove >99% of the incoming mass flow in each stage, ensuring that by the third stage furthest from the target, turbomolecular pumps are able to operate in a nominal ~mTorr range. We anticipate full system testing with helium in mid 2019. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP033 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP034 | A Modular Optical Firing Interface for CERN’s Generic Power Converter Control Platform | 1315 |
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| The power converters group at CERN has developed a third generic converter controller (FGC3) and regulation platform (RegFGC3), capable of controlling any of CERN’s power converters. This platform provides electrical connections to the low-level control elements of power converters, and in some cases a galvanic isolation is required between the converter controller output, and the power converter under control. To meet these requirements, a generic modular optical firing platform has been developed, which converts the electrical firing pulses from the RegFGC3 and FGC3 platforms into optical drive signals. Designed to be fully scalable, this platform provides various protection mechanisms to verify the integrity of the firing information. For example, checking for illegal firing states, dead-time, and drive errors. This paper describes the modular optical firing interface, the basic principles, and the configurations which are in use, or are planned to be used at CERN. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP034 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP035 | Design of the Vacuum System of the FCC-ee Electron-Positron Collider | 1319 |
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| The Future Circular Collider (FCC) Design Study includes the twin storage ring (FCC-ee) where electrons and positrons are stored and made to collide inside two detectors. The vacuum system of FCC-ee must be designed in order to deal with a lower-energy (45.6 GeV), high-current (1390 mA) Z-pole machine and at a later stage with a higher-energy (182.5 GeV) low-current (5.4 mA). The former machine is the most challenging one from the point of view of vacuum, since the photon-stimulated desorption (PSD) generated by the copious synchrotron radiation (SR) fans is quite large. While several concepts have been considered at the beginning, the design retained for the Conceptual Design Report (CDR) is one where the cross-section of the vacuum chamber (VC) in the arcs is a scaled-down version of the one implemented in the SUPERKEKB collider. Contrary to SUPERKEKB tough, the SR fans are absorbed by many short absorbers, with average spacing of 5.8 m. This allow a localization of the PSD gas load and to place lumped pumps in front of the SR absorbers, to maximize the pumping efficiency. The VC design is compatible with the design of the common-yoke dipoles and quadrupoles. The VC material is copper alloy. Optimization of the pressure profiles has been carried out by means of extensive coupled montecarlo simulations, for SR and molecular flow. For the higher energy versions of the machine, for which the SR spectra are characterized by critical energies well above the Compton edge, the localized absorbers facilitate also shielding the tunnel and any radiation-sensitive machine components from X-ray photon damage, by installing short high-Z material around the absorbers. The major features of the CDR relevant for vacuum will be highlighted in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP035 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP036 | Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kararesults on the Fcc-Hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara | 1323 |
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Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305. In the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations. This activity has been carried out in the framework of the EuroCirCol* collaboration (work package 4 "Cryogenic Beam Vacuum System"). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP036 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP037 | Recent Developments of Monte-Carlo Codes Molflow+ and Synrad+ | 1327 |
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Molflow+ and Synrad+ are Monte Carlo simulation tools for ultra-high vacuum and synchrotron radiation, respectively. Over the years they have become a common tool for designing and analysing the vacuum system of particle accelerators. This contribution gives a short summary about new features added since IPAC-14*. Some highlights: In traditional Monte Carlo simulations, one simulated ’virtual’ particle represents a given number of physical molecules or photons. This is a weakness where the pressure or flux of the simulated system spans across multiple orders of magnitude. Synrad now supports low flux mode, a weighed Monte Carlo technique where the represented number of photons is reduced at every reflection, providing significantly better statistics at low flux regions. As for Molflow+, angle maps allow recording the molecules, directional distribution at any point, and then desorb a reduced gas quantity according to the recording. In linear systems, this allows iterative simulations that have been proven to treat systems up to 7 orders of magnitude of pressure difference. Without the new technique the computing time would be prohibitively slow on desktop computers, which is what most users of the two codes use. Both codes now have a built-in geometry builder that allows creating simple models through a set of 3D operations, and modifying those imported from CAD tools. Molflow+ has recently become open source, and it has been made compatible with, and tested on different versions of Linux and macOS. Examples of application of Molflow+ to novel Beam Gas Curtain detector and the design of the FCC-ee vacuum system will be given, alongside with some benchmarking runs against data published in literature.
* M. Ady, R. Kersevan, "Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+", Proc. IPAC’14, Dresden, Germany, June 2014, pp. 2348-2350. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP037 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP038 | Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh | 1331 |
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Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305. EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 1015 H2/m3 with baseline beam parameters within the first months of conditioning. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038 | |
| About • | paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP039 | Data-driven Controller Design Using the CERN Power Converter Control Libraries (CCLIBS) | 1335 |
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| The data-driven control approach is a control methodology in which a controller is designed without the need of a model. Parametric uncertainties and the associated unmodeled dynamics are therefore irrelevant; the only source of uncertainty comes from the measurement process. The CERN Power Converter Control Libraries (CCLIBS) have been updated to include data-driven H-infinity control methods recently proposed in literature. In particular, a two-step convex optimization algorithm is performed for obtaining the 2-degree-of-freedom controller parameters. The newly implemented tools in CCLIBS can be used both for frequency response measurement of the load and for controller synthesis. A case study is presented where these tools are used for an application in the CERN East Area Renovation Project for which a high-precision 900 A trapezoidal current pulse is required with 450 ms flat-top and 350 ms ramp-up and ramp-down times. The tracking error must remain within ± 100 parts-per-million (ppm) during the flat-top (before the ramp-down phase starts). The magnet considered in the case study is of non-laminated iron type, hence the necessity of data-driven techniques since the dynamics of such a magnet is difficult to be modeled accurately (due to eddy currents losses). The Power Converter used is a SIRIUS 2P (with a current and voltage rating of 400 Arms and 450 V, respectively) whose digital control loop is regulated at a sampling rate of 5 kS/s. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP039 | |
| About • | paper received ※ 08 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP040 | Impact of Flux Jumps on High-Precision Powering of Nb3Sn Superconducting Magnets | 1338 |
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| Nb3Sn superconducting magnets represent a technology enabler for future high-energy particle accelerators. A possible impediment, though, comes from flux jumps that, so far, could not be avoided by design unlike for NbTi technology. However, the impact of flux jumps on the powering has not been properly investigated to date. Flux jumps appear during current ramps at relatively low value of current and tend to disappear towards nominal current. They are usually detected as voltage jumps between different magnet coils but they might also produce overall voltage jumps across the magnet electrical terminals. Such jumps might perturb the power converter feedback control loop and therefore potentially jeopardize its precision performance during energy ramps. This work aims at : (i) presenting preliminary experimental test results on some HL-LHC Nb3Sn model and prototype magnets, and (ii) attempting to build a simplified electrical model of the flux jumps (with focus only at its interaction with the power converter feedback control loop). Such work is a starting point for outlining possible power converters control strategies able to minimize flux jumps impact on high-precision powering of Nb3Sn superconducting magnets. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP040 | |
| About • | paper received ※ 23 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP041 | Preliminary Design of RF-Shielded Bellows | 1341 |
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| A new design of RF-shielded bellows is proposed for the TPS to alleviate wake field effects and Joule heating resulting from contact resistance at the contact interface of sliding two dissimilar metals. Most efforts are put into controlling corrosion which is regarded as the main cause of electrical contact degradation. Rh-Au is chosen as a mating interface because they are stable under high temperature condition. Experimental tests are made to find an effective plating thickness of Rh and Au and to determine a suitable normal load applicable on the Rh-Au interface. A preliminary design of RF-shielded bellows that can sustain thousands of cycles during their lifetime is under testing. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP041 | |
| About • | paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP042 | The Beam Cleaning Analysis for the TPS Vacuum System | 1344 |
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| Commissioning for the TPS, a low-emittance 3-GeV synchrotron ring, started in December 2014 and is now currently operating in top-up mode at 400mA for users. Until the last machine shut down in December 2018, a total beam dose of 4919 Ah was accumulated and the beam cleaning effect decreased the dynamic pressure to 1.5×10-11 Pa/mA. During past years operation, several vacuum chambers were replaced to improve vacuum performance and avoid exposure to synchrotron radiation from insertion devices. In this paper, the beam cleaning evolution of new vacuum sections will be discussed and compared with experience in the rest of the storage ring. A particular cleaning evolution could be predicted and can be referenced for machine shutdown planning in the future. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP042 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP044 | Special Aluminum Gasket Sealing of Non-circular Profile Flanges for the Accelerator UHV Systems | 1347 |
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| Most of the beam ducts for the accelerators are not regularly the circular profile. Unfortunately, the conflat (CF-) flanges and the gaskets with non-circular profile were not commercially available. Besides, additional RF-contact bridges between the flanges must be built in for mitigating the impedance from the flange-gaps. In this presentation, various types of the aluminum (Al-) gaskets designed for the non-circular profile Al-flanges for the accelerator ultrahigh vacuum (UHV) systems are introduced. The surface of the Al-flange is flat to accommodate the special Al-gasket with knife edges for the sealing. Both the flange and gasket are manufactured by the oil-free Ethanol-CNC-machining process that any non-circular profile, e.g. rectangular, race-track, key-hole, etc., flanges can be precisely produced. The inner diameters of the gasket just suits those of the flanges that the impedance from the gap is significantly reduced. The flanges and gaskets after oil-free machining can be assembled immediately without any chemical cleaning. The experimental results for the as-mentioned non-circular profile Al-flanges reveal the UHV quality at pressure < 20 nPa after vacuum baking. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP044 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP045 | The Protection Instrument for Cryogenic Phase Separator Pressure Relief Valve of TPS Beamline | 1350 |
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| TPS (Taiwan Photon Source) beamlines have operated for three years after the successful commission in 2015. Recently, the electromagnetic activated pressure relief valve of cryogenic phase separator of beamline had malfunction due to the rust of its control circuits. After on site observation and temperature records, the water was found to be condensed around the outlet area due to fast temperature dropping near the valve as it was activated. Such situation would cause the rust of metal components due to humidity after a certain period of time. To avoid such event, fan is used to blow the condensed water and silicone heat belts are added to increase the local temperature with unique designed clamp for fixing the fan, sensors and safety circuit breaker. Via the temperature control system, the temperature monitoring, setting and the abnormal situation can be access on web page through Ethernet to make sure the proper operation of the protected devices. The instrument has been operated since Dec. 2018. After four months of operation, the moist situation has been improved and the relief valve is no longer frosted. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP045 | |
| About • | paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP046 | Improvement the Bending Magnet Power Supply Performance for TPS Storage Ring | 1353 |
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| In the TPS (Taiwan Photon Source) facility, current stability of the electron beam depends on the bending magnet power supply and an orbit FOFB system to compensate the magnetic field. Due to the output current stability of the bending magnet power supply drifts with temperature so the orbit FOFB system should be applied to fine tune magnetic field and the photon beam should circulate in storage ring. In this paper, to stabilize the temperature of regulation circuit’s temperature box of the bending magnet power supply, the long-term output current stability is improve from ± 50ppm to ± 10ppm, and orbit FOFB system substantially reduce the tune X of beam position, effectively increasing the beam current stability and quality. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP046 | |
| About • | paper received ※ 12 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP047 | Upgrade of the Cryogenic Control System for SRF Modules at the Taiwan Light Source | 1356 |
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| An upgrade of the cryogenic control system for superconducting radio-frequency (SRF) modules of the Taiwan Light Source (TLS) has been completed. The biggest challenge was to recover all protection and operational functions, while minimizing the quantity of vented helium from SRF modules while replacing valve controllers. Gradually, this work was finished within several one- and ten-day scheduled machine shutdown periods for accelerator maintenance. No large helium vent nor pollution of the cryogenic system occurred during all component replacements and function verifications. Functions of the cryogenic electronics were improved, whereas the valve controllers are upgraded to new versions to increase reliability and availability. Communications with the data acquisition system was also secured by buffered signal processing module so that device shutdown of the data acquisition system will not interrupt the cryogenic valve operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP047 | |
| About • | paper received ※ 29 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP048 | Current Status of Turkish Accelerator and Radiation Laboratory | 1359 |
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Funding: T.R. Presidency Strategy and Budget Office Grand No: 2006K-120470 Turkish Accelerator and Radiation Laboratory (TARLA) which is designed to deliver various accelerator based radiation sources, aims to be outstanding research instrument for users from both Turkey and region. Within the current scope of TARLA its superconducting accelerator will drive two of free electron laser (FEL) beamlines in order to provide Continuous Wave (CW) tunable radiation of high brightness in the mid- and far-infrared range as well as a Bremmstrahlung radiation station. Main components of TARLA, such as injector, superconducting accelerating modules and cryoplant are under commissioning currently. In this paper commissioning results and current status of facility are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP048 | |
| About • | paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP050 | Conceptual Design of the Diamond-II Vacuum System | 1362 |
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| The conceptual design of the vacuum system for the Diamond-II storage ring upgrade is described. Due to the small vessel cross section, typically 20 mm inside diameter (ID), and the consequent conductance limitation, distributed pumping is provided by non-evaporable getter (NEG) coating supplemented by ion pumps at high gas load locations. In-situ bakeout is incorporated to allow rapid recovery from both planned vacuum interventions and unplanned vacuum events. The vacuum vessels are constructed mainly from copper alloy while stainless steel is used in regions of AC magnets requiring low electrical conductivity. The proposed layout, engineering and build sequence of the vacuum system are described along with gas flow simulations confirming the vacuum performance advantages of NEG-coated vessels compared with uncoated vessels. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP050 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP051 | MULTIPACTOR SUPPRESSION BY LASER ABLATION SURFACE ENGINEERING FOR SPACE APPLICATIONS | 1365 |
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| Developing a surface with low Secondary Electron Yield (SEY) is one of the main ways of mitigating electron cloud and beam-induced electron multipacting in high-energy charged particle accelerators and space-borne RF equipment for communication purposes. In this study we report on the secondary electron yield (SEY) measured from silver coated aluminium alloy as-received and after laser ablation surface engineering (LASE). Analysis shows the SEY can be reduced by 43% using LASE. EDX and SEM analysis shows it is possible to reduce the SEY whilst maintaining the original surface composition. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP051 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP053 | Test Results of the Low-Stored-Energy -80 kV Regulator for Ion Sources at LANSCE | 1369 |
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Funding: Work supported by the U. S. Department of Energy. The H− ion source at the LANSCE accelerator facility uses an 80 kV accelerating column to produce an H− ion beam. A regulated power supply maintains the source and support equipment racks at -80kV with respect to local ground. As the facility’s H− beam currents have been increased, voltage droop on the regulated -80 kV power supply has become one of the limiting factors on beam current. The previous regulator used a standard 120kV DC HV supply and a high power planar triode in series to regulate the voltage down to 80 kV and to stop the flow of current during an arcdown of the -80 kV accelerating column. In 2018 we devised a method of using a pair of standard, 50 kV capacitor charging supplies to produce the required 80 kV with minimal stored energy and significantly better voltage regulation over the beam pulse. This configuration has been tested on the Ion Source Test Stand and is being considered for installation on the main LANSCE linac. We will present the design, modeling and measured results of the new system as compared with the performance of the previous system. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP053 | |
| About • | paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019 | |
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| TUPMP054 | Investigations on Cryopanels in the Room Temperature Heavy Ion Synchrotron SIS18 | 1372 |
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| The heavy ion synchrotron SIS18 at GSI will serve as injector ring for the FAIR-facility and provide high intensity heavy ion beams. The operation of such beams requires the usage of low charge states, which have high cross sections for ionization. To overcome this issue, many upgrade measure have been realized in the past decade, such as the installation of an ion catcher system with low desorption surfaces and coating 65% of the circumference of SIS18 with NEG to lower the static gas pressure. Since the vacuum dynamics during operation prevent the achievement of the intensity goals for FAIR, new concepts have to be developed, to increase the beam intensity. One idea is the installation of additional pumping speed in the form of cryogenic surfaces. Heavy residual gas components, which have the highest ionization cross sections can be cryopumped at moderate temperatures, i.e. already at 50-80 K. In fact, the only typical residual gas component which can not be pumped via cryosorption in this temperature regime is Hydrogen, which has a factor 50 lower ionization cross sections than Argon, the heaviest residual gas component. In this paper, we present a study of the integration of cryopanels into the vacuum chambers of SIS18. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP054 | |
| About • | paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPMP056 | LANSCE Vacuum System Improvements in the Last ~10 Years | 1375 |
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Funding: DOE/NNSA The Los Alamos Neutron Science Center (LANSCE) accelerator started its operation in 1972. To mitigate the vulnerability due to old equipment and to restore the 120 Hz operation capability we lost a while ago, we have gone through a refurbishment / risk mitigation project since 2007. This paper summarizes the improvements in the vacuum systems in the last ~10 years and shows some data on the downtimes caused by vacuum failures. The refurbished equipment is significantly more maintainable and will contribute to extend the life of this old accelerator, but it has been a challenge to reduce the downtime. Some examples that caused a long downtime will be described. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP056 | |
| About • | paper received ※ 24 May 2019 paper accepted ※ 26 May 2019 issue date ※ 21 June 2019 | |
| Export • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |