MHI, Kobe
MHI's activities for ILC project will be shown.
TU Darmstadt, Darmstadt
The superconducting cavities of the S-DALINAC have a high loaded quality factor and are very susceptible to microphonics. To stabilize the amplitude and phase of the cavities' fields an analog control system has been used for 20 years. To improve the stability and the availability of the low level RF control system it is currently replaced by a digital one. The 3 GHz signals coming from the cavities are converted down to the base band using hardware I/Q demodulators. The base band signals are digitized by ADCs and fed into an FPGA. This FPGA contains a custom CPU which executes the code implementing the control algorithm. The computed control signal is I/Q modulated before it is send to the cavity again. The superconducting cavities are operated with a self-excited loop algorithm whereas a generator driven algorithm is used for the low Q normal conducting bunching cavities. A 6 GHz RF board allows the operation of a new 2f buncher. Parameters can be adjusted via an EPICS IOC running on a standard PC. All signals from the FPGA can be monitored in realtime by the operator.
SKKU, Suwon
PAL, Pohang, Kyungbuk
The low level RF (LLRF) control system for PLS is being upgraded to improve the performance of the system. The LLRF control system under development consists of FPGA, and high speed ADC and DAC as well as analog front-end devices which process the signal from cavity and to RF high power system. In addition, it utilizes digital signal processing technology based on FPGA. In order to optimize the accelerating electric field in the cavity, it is required to maintain field stability less than ±1% in amplitude and 1° in phase. And the resonance condition of the cavity should be monitored and controlled. The various digital signal processing theories such as digital filters, Cordic, PI control enable to meet these requirements and to control the feedback signal less than a microsecond. The LLRF control system is also equipped with the Ethernet by the cPCI. The preliminary design study on the LLRF control system for PLS superconducting cavity will be described in this paper.
ODU, Norfolk, Virginia
Review of the theory, design and applications of Spoke cavities, with particular emphasis on SRF spoked cavities. Aspects of low level RF control for spoke cavities will also be presented.
KEK, Ibaraki
JAEA/ERL, Ibaraki
ISSP/SRL, Chiba
A construction of the Compact ERL is planned in KEK, Japan. A demonstration of the performance of the main linac super-conducting accelerating system is one motivation of the project. We have been designing a cryo-module, which works under CW operation, and contains two 9-cell cavities, with input couplers, frequency tuners and HOM dampers. Most of these components have been specially developed for ERL operation. Two proto-type of the 9-cell cavity were constructed. First one was vertically tested and suffered from field emissions. Second one is now waiting a measurement. High power component tests have been carried out for input coupler. At first, large temperature rise was observed at a ceramic window part due to unexpected dipole resonance. After that, new version of window was designed and successfully passed 20kW CW power with reflection. Proto-types of HOM damper were also constructed. Cooling tests have been performed for them to verify cooling ability against more than 100W heat load, under vacuum condition. A cryo-module will be completed in 2012, and cooling tests and beam tests will follow.
Fermilab, Batavia
DESY, Hamburg
A Third Hamonic/3.9 GHz superconducting RF module was recently installed in the FLASH facility at DESY. Ultra short bunches with high peak current are required to efficiently create high brilliance coherent light and these can be produced by means of a 2-stage transverse magnetic chicane bunch compression scheme coupled with off-crest acceleration. The long bunch tails and reduced peak current which result from the nonlinearities of the RF since wave can be eliminated by the addition of a 3rd harmonic RF system. Such a system can also allow for the creation of uniform intensity bunches of adjustable length necessary for seeded operation. We present here a summary of commissioning and early operating experience of the newly-installed device.
KEK, Ibaraki
MHI#10 and #11 cavities are measured in KEK-STF as the s0 plan for ILC. After these vertical tests, they will be sent to J-Lab and tested at least once there. Moreover, two new cavities without HOM coupler are fabricated and measured in STF, which are made by two new vendors (HITACHI and TOSHIBA). As the international collaboration, one cavity from IHEP in Beijing will be sent to KEK, optical inspected, high pressure rinsed and vertical tested. Although MHI#8 cavity for S1-Global reached 38MV/m, it could not achieve ILC specification (35MV/m, 0.8x109) due to the heavy field emission. To overcome this problem, the various tests were done in the stage of the surface treatment. For example, the EP parameters and the rinsing procedure were changed. In this report, the recent results of the vertical tests including the surface treatment in KEK-STF will be presented in detail.
LANL, Los Alamos, New Mexico
JLAB, Newport News, Virginia
An update on the study of 805 MHz elliptical SRF cavities that have been optimized for high gradient will be presented. An optimized cell shape, which is still appropriate for easy high pressure water rinsing, has been designed with the ratios of peak magnetic and electric fields to accelerating gradient being 3.75 mT/(MV/m) and 1.82, respectively. A total of 3 single-cell cavities have been fabricated and tested with various conditions. In addition, a 6-cell cavity design has been completed including multipacting simulations.
JLAB, Newport News, Virginia
As of September 2009 a sustainable 1 MW in beam power was achieved at Oak Ridge, continuing to make SNS the highest energy-pulsed neutron source available for scientific research worldwide. This paper evaluates the FPCs designed and built at JLAB for the SNS project, emphasizing their performance and related issues addressed during prototyping, qualification on the RF power test stand at room temperature, superconducting cavity commissioning and successful but challenging operation with beam for more than 5 years.
Mircea. Stirbet@jlab.org
DESY, Hamburg
The FLASH RF system consists of several RF stations, which provide RF power up to 10MW at 1.3GHz, 1.3ms and 10Hz repetition rate, each, for the superconducting cavities and the RF gun of the FLASH linear accelerator. During the last upgrade of the FLASH facility several modifications have been made also to the RF system. The oldest RF stations were constructed and manufactured by FNAL more than 15 years ago and have been replaced. Since one additional superconducting accelerator module has been added and one superconducting module and the RF gun have been replaced, modification and rearrangement of the RF waveguide distributions were required. An XFEL type waveguide distribution for the new accelerator module ACC7 and a distribution without individual phase shifters for the exchanged module ACC1 have been installed. A new waveguide distribution for the RF gun allows phase tuning by changing the gas pressure in the waveguides. It will also allow supply the RF gun by a 10MW multi beam klystron instead of the still used 5MW single beam klystron at a later point of time.