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| TUPKF051 | A 500 kV Power System for a Gridded Sheet-beam Klystron | positron, focusing, plasma, cathode | 1066 | ||
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The Next Generation Linear Collider (NLC) will require hundreds of X-band high power klystrons. These klystrons are typically cathode pulsed at 500 kV and 265 A each, with 1.6 microsecond pulses of RF, and a complex microwave delay line to achieve 400 ns RF pulses. Because the pulsed voltage is so high, CV2f losses will lead to many millions of dollars per year of wasted power. The klystron group at SLAC, working with Calabazas Creek Research (CCR), is developing a gridded, sheet beam klystron. This new klystron design avoids the CV2 losses of cathode pulsing because its cathode is not pulsed - it remains at a constant high voltage. Instead, the grid voltage is pulsed over a much smaller (6 kV) voltage range. This paper will describe DTI's progress in development of the electronics required to drive this new klystron, including a 500 kV multiplier power supply and grid modulator, a multi-concentric high voltage cable, which also acts as the pulse forming line, and an advanced, reentrant cable connection to the klystron itself. This design allows the klystron to be located adjacent to the beamline, and separated from the power electronics, improving RF efficiency, maintainability, and overall reliability.
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| TUPKF063 | Current Status of the Next Linear Collider X-band Klystron Development Program | positron, plasma, impedance, booster | 1090 | ||
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Klystrons capable of driving accelerator sections in the Next Linear Collider have been developed at SLAC during the last decade. In addition to fourteen 50 MW solenoid-focused devices and a 50 MW Periodic Permanent Magnet focused (PPM) klystron, a 500 kV 75 MW PPM klystron was tested in 1999 to 80 MW with 3-microsecond pulses, but very low duty. Subsequent 75 MW prototypes aimed for low-cost manufacture by employing reusable focusing structures external to the vacuum, similar to a solenoid electromagnet. During the PPM klystron development, several partners (CPI, EEV and Toshiba) have participated by constructing partial or complete PPM klystrons. After early failures during testing of the first two devices, SLAC has recently tested this design (XP3-3) to the full NLC specifications of 75 MW, 1.6 microseconds pulse length, and 120 Hz. This 14.4 kW operation came with a tube efficiency of 50%. The XP3 3 average and peak output power, together with the focusing method, arguably makes it the most advanced high power klystron ever built anywhere in the world. Design considerations and the latest testing results for these latest prototypes will be presented.
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| WEPKF051 | Operational Analysis of PLS 2-GeV Electron Linac Klystron-modulator System | alignment, kicker, bunching, site | 1720 | ||
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The klystron-modulator(K&M) system of the Pohang Light Source(PLS) had been supplying high power microwaves for the acceleration of 2 GeV electron beams. There are 11 sets of K&M systems to accelerate electron beams to 2 GeV nominal beam energy without operating one klystron-modulator. One module of the K&M system consists of an 80 MW S-band (2856 MHZ) klystron tube and the matching 200 MW modulator. The total accumulated high-voltage run-time of the oldest unit among the 12 K&M systems has reached nearly 68,000 hours as of Dec. 2003 and the summation of all the units' high voltage run-time is approximately 820,000 hours. The overall system availability is well over 95%. There have been continuous efforts to improve the klystron-modulator system more stable and reliable. To improve self-diagnostic, operation, monitoring, and remote communication, we developed a new modulator controller based on an industrial PC platform in 2002. In this paper, we are able to review overall system performance of the high-power K&M system and the operational characteristics of the klystrons and thyratrons, and overall system's availability analysis from Jan. to Dec. 2003.
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| WEPKF053 | Status and Development for the JAERI ERL-FEL for High-Power and Long-Pulse Operation | alignment, kicker, bunching, site | 1723 | ||
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After the success of energy recovery linac (ERL) for the superconducting free-electron laser (FEL) in the Japan Atomic Energy Research Institute (JAERI), the JAERI ERL-FEL has been upgrading for high-power and long-pulse operation. The new grid pulser for the thermoionic cathode gun is under development and test to increase the beam current by increasing the repetition rate of 10MHz to 20MHz. The new RF sources of CW mode for higher power for non-energy-recovery parts have been installed and tested for long-pulse operation. The properties of the superconducting linac required for the long-pulse operation were also measured such as pressure in the cryomodule, vibration of frequency and piezo tuner response. The RF control systems have been also upgraded to reduce the fluctuation to less than 0.1% for amplitude and 0.1 deg for phase.
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| WEPKF054 | Auto-filling Cryogenic System for Superconducting Wiggler | alignment, kicker, bunching, site | 1726 | ||
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A 3.2 Tesla superconducting wiggler with period length of 6.0 cm (SW6) was installed in January of 2004 at the National Synchrotron Radiation Research Center (NSRRC). A cryogenic plant for superconducting rf cavity will also provide liquid helium and liquid nitrogen for SW6 by using an independent automatic filling system. To facilitate a stable and precise auto-filling process, a PID controller, the kernel of the auto-filling system, will control the valves of liquid helium and liquid nitrogen, respectively. The authors shall present the control algorithm of different operation modes, namely the pre-cooling mode and normal auto-filling mode. The boil off rate of liquid helium and liquid nitrogen will be discussed.
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| WEPKF055 | Design and Implementation of a Switching Mode Bipolar Power Stage of the Correction Power Supply | alignment, kicker, bunching, site | 1729 | ||
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In order to enhance efficiency of the correction power supply, the switching mode bipolar power stage was to implement and to substitute for the original power stage of the correction power supply. To ensure higher efficiency, the programming dc bus voltage of the power stage of the correction power supply must be working in accordance with the output current state and load. A new power conversion stage was constructed and employs power MOSFET operating at higher switching frequency then old 60 Hz energy conversion mode system. This will not only improve the efficiency but also decrease the weight of the correction power supply. The new switching mode power stage supply a bipolar power dc bus power and automatic turning working voltage by the feedback balance circuit. Results and working performance will be presented in this paper.
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| WEPKF056 | Reducing Output Current Ripple of Power Supply with Component Replacement | alignment, kicker, bunching, site | 1732 | ||
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Correction magnets of synchrotron storage ring are served with linear power supplies (correction power supply) with 100 ppm output current ripple in National Synchrotron Radiation Research Center. Reducing output current ripple of correction power supply might reduce perturbation of beam position of storage ring. Replace correction power supplies with lower output current ripple ones is straightforward but costs lots of money. Without adding any other circuit and electronic component, some components of correction power supply are replaced by ones with more precious and lower output fluctuation; so that the same circuitry structure of correction power supply is kept without increasing its complexity and could reach 25 ppm output current ripple.
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| WEPKF057 | Design and Study of a Superferric Model Dipole and Quadrupole Magnets for the GSI Fast-pulsed Synchrotron SIS100. | alignment, kicker, bunching, site | 1735 | ||
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New experimental results from the investigation of a model superferric Nuclotron-type dipole and quadrupole magnets are presented. The magnets operate at pulse repetition rate f = 1Hz, providing peak magnetic field B = 2 T and the field gradient G = 34 T/m in the dipoles and quadrupoles respectively. The superconducting coil is made from a hollow multi-filamentary NbTi cable cooled with two phase helium flow. Different possibilities were investigated to reduce AC power losses in the case of a cold iron yoke (T=4.5K). The achieved results are discussed. The value of 9W/m has been obtained for dipole magnet with the yoke at T=50K. The first 50 K yoke quadrupole was designed and tested. Other problems, connected with the magnetic field quality, mechanical and cryogenic stability of the magnets under SIS100 operating conditions are also discussed.
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| WEPKF060 | Bending Magnets for the SAGA Storage Ring: Manufacturing and Magnetic Measurements | alignment, kicker, bunching, site | 1738 | ||
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The paper describes the design, the manufacture and the magnetic measurement of the dipole bending magnets (BM) for SR Source storage ring (prefecture SAGA, Japan) carried out in BINP, Novosibirsk, Russia. The requirement was to create the laminated C-shape BMs with the 3.2 m radius and parallel edges. The magnetic field homogeneity must be not worth than ±2? 10-4 inside the working area: H = 30+40mm and V = ±20mm at 0.26T (250 MeV), and H = ± 28mm and V = ±20mm at 1.46 T (1.4GeV). The BMs were designed on the basis of the 2-D 3-D modeling taking into account the laminated core. The BMs yokes were produced with the help of the technology of the high temperature gluing. The computer simulations are in a good agreement with the magnetic measurements. The main parameters of the magnetic fields satisfy to the requirements and are presented. The features of the design, manufacturing and precise magnetic measurements of SAGA BMs are discussed.
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| WEPKF061 | Study of Electrical Steel Magnetic Properties for Fast Cycling Magnets of SIS100 and SIS300 Rings | alignment, kicker, bunching, site | 1741 | ||
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The operation conditions of yoke steels in superconducting magnets of the SIS100 and SIS300 are at 4.2 K and unipolar cycles with high magnetic induction. The results of measurements of different classes of electrical steels, both isotropic and anisotropic, in the operating conditions of superconducting dipoles are presented. The measurements are carried out on ring samples in quasistatic mode. Dependence of B(H) as well as values of Hc and hysteresis losses in bipolar and unipolar cycles are determined from hysteresis loops at different temperatures. The anisotropy of steels is measured at room temperature on the strip samples, cut along the rolling direction and across one. The comparison of results on ring and strip samples is carried out. The results of calculations of hysteresis and eddy current losses in iron yoke of fast-cycling dipole for the SIS300 are presented. The recommendations on choice of grade steels for fast cycle superconducting magnets are given.
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| WEPKF062 | Study of the Quench Process in Fast-cycling Dipole for the SIS300 Ring | alignment, kicker, bunching, site | 1744 | ||
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The results of numerical quench process simulation in the coil of superconducting dipole with magnetic field of 6 T and 100-mm aperture for high-energy ion and proton synchrotron facility SIS300 are presented. The peculiarities of quench process developed in dipole are discussed for several variants of quench conditions. The coil quench behavior determines the features, scopes, and limitations in possible quench protection scheme. Main design characteristics of the preferable protection system are considered.
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| WEPKF063 | Comparison of Three Designs of Wide Aperture Dipole for SIS300 Ring | alignment, kicker, bunching, site | 1747 | ||
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The GSI Fast-Pulsed Synchrotron Project is found now under development. The last stage of this machine is the SIS300 ring, which will use superconducting dipoles with 100-mm aperture, 6-T magnetic field amplitude and 1-T/s field ramp rate. This dipole has to posses minimal heat losses both in the coil and in the iron yoke. This article considers three designs of such dipole. The main distinction of these designs is the different thickness of stainless steel collars, which are supported the coil. The collars in the first design hold all forces arisen in the magnet. The second design needs collars only for assembly of the coil and cooling down of the magnet. An iron yoke in this design will withstand ponderomotive forces. The third design has no collars and the iron yoke will hold all forces, including preload, forces originated during cooling down and ponderomotive forces. The different mechanical, magnetic and thermal characteristics are presented and comparative analysis of these designs is carried out.
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| WEPKF064 | Methods for Reducing Cable Losses in Fast-Cycling Dipoles for the SIS300 Ring | alignment, kicker, bunching, site | 1750 | ||
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A new synchrotron facility is being designed for the acceleration of high intensity and high-energy ion and proton beams at GSI, Darmstadt. The main magnetic elements of the second stage (SIS300) are superconducting dipoles with 100 mm aperture, 6-T magnetic field amplitude, and 1 T/s field ramp rate. The main requirements for these magnets, in addition to high field quality, are minimal heat losses, both in the coil and in the iron yoke, at an acceptable temperature margin. An increase of the temperature margin can be achieved by increasing the volume of superconductor in the cable. However, increasing the number of strands in the cable results in a growth of the cable width. Since coupling losses in the cable are proportional to the fourth power of cable width, these losses rise dramatically. This presentation considers and analyses different ways of reducing these cable heat losses. The calculated results of heat losses for different geometries, based on various cable designs, as well as the parameters of optimal cable designs, based on computer simulations, are presented.
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| WEPKF065 | Study of Thermal Stability and Quench Process of HTS Dipole | alignment, kicker, bunching, site | 1753 | ||
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The dipole with a coil made from HTS composite on a Bi2223 basis and placed in the ferromagnetic yoke has been developed and produced in IHEP. A designed magnetic field of the dipole in 20-mm aperture is 1 T at temperature of liquid nitrogen. The numerical analysis of factors, having influence on thermal stability of the magnet, as well as the computer simulations of dipole heating during quench was carried out. An anisotropy of voltage-current characteristics of HTS tapes in a magnetic field is taken into account in calculations of quench process. The measured results of voltage-current characteristics during powering and quench of the coil are in a good agreement with the numerical calculations
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| WEPKF066 | Stability of Fast-cycling Dipole for SIS300 Ring | alignment, kicker, bunching, site | 1756 | ||
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Funding AgencyShould not exceed 200 charactersFootnotesFootnotes: Not exceeding 200 chaThe main requirement to the superconducting dipole with 100-mm aperture, 6-T magnetic field amplitude and 1-T/s field ramp rate for the SIS300 accelerator, developed in the GSI, Darmstadt, is a stability of the magnet influenced by various heat releases arising during operation mode. The computer simulation of the heating of superconducting dipoles and cooling helium during the SIS300 operating cycle was carried out. The analysis of stability is based on the numerical solution of the heat balance equation in the coil and in a single?phase helium flow. Temperature margin of the superconducting dipole during the SIS300 operating cycle was calculated. Possible ways to increase the temperature margin are discussed.
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| WEPKF068 | Developments in Magnet Power Converters at the SRS | alignment, bunching, site, beamloading | 1759 | ||
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A project to upgrade the magnet power converters of the SRS has commenced to ensure its efficient operation for its remaining operational lifetime. A recent risk analysis of the facilities equipment identified that the main areas for concern were the Storage Ring magnet power converters, kicker and septum pulse power supplies and the Booster Dipole "White Circuit" and associated power converters. This report detail the development and replacement programs currently active at Daresbury Laboratory, including future work identified to support and improve SRS utilisation.
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| WEPKF069 | 52 kV Power Supply for Energy Recovery Linac Prototype RF | alignment, bunching, site, beamloading | 1762 | ||
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Daresbury Laboratory is constructing a Radio-Frequency (RF) Test Facility to be capable of testing RF cavities for accelerator applications. Electrical power for the RF equipment will be provided from an existing -52 kV 6-pulse rectifier and transformer system capable of delivering 16A DC continuous current. A crowbar circuit will be provided to divert the large amount of stored energy in the smoothing capacitor bank in the event that a spark should occur between the cathode and the body or modulating anode. Traditionally, the crowbar has been provided by using an ignitron, but modern solid state devices have sufficient performance to meet the requirements. This paper discusses the numerous design options that were considered for the circuit parameters.
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| WEPKF070 | Design Issues for the Superconducting Magnet that goes around the Liquid Hydrogen Absorber for the Muon Ionization Cooling Experiment (MICE) | vacuum, focusing, alignment, bunching | 1765 | ||
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This report describes the design issues that are associated with a superconducting focusing solenoid that goes around a liquid hydrogen absorber for the Muon Ionization Cooling Experiment (MICE) proposed for the Rutherford Appleton Laboratory. The solenoid consists of two superconducting coils that may operated at the same polarity or at opposite polarities. As a result, the coils and their support structure must be designed to carry a 300 ton inter-coil force that is forcing the coils apart along their axis. The basic design parameters for the focusing magnet are discussed. The magnet and its cryostat are designed so that the absorber can be assembled and tested before installation into the pre-tested focusing solenoid. A safety requirements for MICE dictate that the insulating vacuum for the superconducting magnet be separated from the insulating vacuum for the absorber and that both vacuum be separated from the experiment vacuum and the vacuum within adjacent RF cavities. The safety issues associated with the arrangement of the various vacuums in the MICE focusing modules are presented. The effect of magnet operation and magnet quench on the liquid hydrogen absorber is also discussed.
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| WEPKF071 | A New Current Regulator for the APS Storage Ring Correction Magnet Bipolar Switching Mode Power Converters | vacuum, focusing, alignment, bunching | 1768 | ||
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The correction magnets in the Advanced Photon Source's storage ring are powered by PWM-controlled bipolar switching-mode converters. These converters are designed to operate at up to ± 150 A. The original current regulator used a polarity detection circuit, with a hysteresis, to determine which IGBT was needed to regulate the current with a given polarity. Only the required IGBT was switched while others were held on or off continuously. The overall IGBT switching losses were minimized by the design. The shortcoming of the design is that the converter's output is unstable near zero current because of the hysteresis. To improve the stability, a new current regulator, using a different PWM method, has been designed to eliminate the requirement of the polarity detection. With the new design, converters can operate smoothly in the full range of ±150 A. The new design also meets tighter specs in terms of the ripple current and dynamic response. This paper describes the design of the new regulator and the test results.
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| WEPKF072 | Clearing Electrodes for Vacuum Monitoring at the Fermilab Recycler | focusing, alignment, bunching, site | 1771 | ||
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The Fermilab Recycler is a fixed 3.3-km 8-GeV kinetic energy storage ring located in the Fermilab Main Injector tunnel. Each split-plate beam position monitor in the Recycler is also used to generated an ion clearing field for ions trapped by the antiproton beam. Approximately 100 locations have been instrumented with pico-amp meters to measure the electron current, generated by the beam-ionized residual gas in the vacuum chamber. This electron current is found to be proportional to the beam current and to the residual gas pressure in the Recycler and may be used to monitor the Recycler vacuum.
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| WEPKF073 | 2nd Generation LHC IR Quadrupoles Based on Nb3Sn Racetrack Coils | focusing, alignment, bunching, site | 1774 | ||
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After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the baseline NbTi low-beta quadrupoles with a higher performance magnets based on advanced superconducting materials and magnet technologies is one of the most straightforward ways in this direction. Preliminary studies show that high-performance Nb3Sn strands to be available within the next few years allow increasing the quadrupole aperture up to 110 mm using a 4-layer shell-type coil and providing the same 200 T/m field gradient with 20% margin as the baseline magnets. It will allow reduction of b* by a factor of 3. An alternative approach to the quadrupole design is based on simple flat racetrack coils. This paper discusses the possibilities and limitations of large-aperture racetrack quadrupole designs and compares them to the shell-type magnets.
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| WEPKF074 | Magnetic Field Measurements of the LHC Inner Triplet Quadrupoles Produced at Fermilab | focusing, bunching, site, quadrupole | 1777 | ||
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Production of 18 superconducting low-beta quadrupoles (MQXB) for the LHC is well advanced. These 5.5 m long magnets are designed to operate at 1.9 K with a peak field gradient of 215 T/m in the 70 mm apertures. Two MQXB cold masses with a dipole orbit corrector between them form a single cryogenic unit (LQXB) which is the Q2 optical element of the final focus triplets in the LHC interaction regions. A program of magnetic field quality and alignment measurements of the cold masses are performed at room temperature during magnet fabrication and LQXB assembly as well as at superfluid helium temperature. Results of these measurements are summarized in this paper.
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| WEPKF075 | Measurements of Sextupole Decay and Snapback in Tevatron Dipole Magnets | focusing, bunching, site, quadrupole | 1780 | ||
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To optimize the performance of the Fermilab Tevatron accelerator in Collider Run II, we have undertaken a systematic study of the drift and subsequent snapback of dipole magnet harmonics. The study has mostly focused on the dynamic behavior of the normal sextupole component, b2, as measured in a sample of spare Tevatron dipoles at the Fermilab Magnet Test Facility. We measured the dependence of the decay amplitude and the snapback time on Tevatron ramp parameters and magnet operational history. A series of beam studies was also performed [*]. This paper summarizes the magnetic measurement results and describes an optimization of the b2 correction scheme which is derived from these measurements.
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* P.Bauer et al. These proceedings. |
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