ORNL, Oak Ridge, Tennessee
Solid-state based high-power modulators utilize new technology, yet must meet the operational needs of a high reliability facility. This modulator technology is in use at SNS, and is under consideration and development for future machines, such as the ILC and PEFP. Through operational experience and a sustained development effort, a number of improvements have been deployed in the SNS modulator system to meet the high availability demands of operating facilities. The operating experience and development effort of the world-wide community will also be reviewed.
CLASSE, Ithaca, New York
Funding: National Science Foundation
Diagnosing field-limiting behavior in multi-cell superconducting cavities can be difficult due to the lack of direct local measurements of cavity surface properties. The results of multiple vertical tests on several 5-cell vertically electropolished 1.3GHz superconducting cavities with measurements of cavity surface properties are presented. A combination of oscillating superleak transducer and resistive thermometry data for various accelerating passband modes are used to infer the field-limiting mechanism for several cells of each multi-cell cavity.
CIAE, Beijing
Department of Physics, Central China Normal University, Wuhan
Light II-A pulsed power generator was used as a power driver of pumping KrF laser at CIAE. The redesign of Light II-A pulsed power generator is based on the consideration that the machine will consist of one single Marx generator with two different experimental lines，which is presented in this paper. The original experimental line with characteristic impedance of 5Ω is remained, and a new line of low impedance (about 1.5Ω ) is added to the Marx generator. The structure design and the electric insulation design are introduced. It is also outlined here the manipulation of modeling the dynamic behavior of gas discharge arc as well as the circuit simulation results of the two experimental lines. Meanwhile a brief introduction is given to the potential application of the low impedance line.
CAEP/IFP, Mainyang, Sichuan
Funding: Hongtao Li is with the Institute of Fluid Physics, China Academy of Engineering Physics (CAEP), Mianyang City, Sichuan, China. (Fax:86-816-2282695; e-mail: lht680526@ 21cn.com).
In order to study the physics of fast Z-pinches and research the key issues of pulse power technology, a 10MA/6MV z-pinch primary test stand (PTS) composed of 24 modules will be built in IFP. The prototype module adopted capacitive storage scheme is composed of the 6MV/300kJ Marx-generator (MG), intermediate storage capacitor (IC), laser-triggered switch (LTS), pulse forming line (PFL), water self-breakdown switch (WS), and tri-plate pulse transmission line (PTL). The measured output current of the prototype is approximate 520kA, and output voltage is approximate 2.1MV. The unique multi-stage LTS based on uniform field distribution design and multi-pin unsymmetrical WS make the prototype modules have low systemic delay jitter which is necessary for synchronization of multi-module facility. 1-δ jitter of delay of the system is less than 4ns.
IHEP Beijing, Beijing
The prototype of pulsed power supply for injection painting bump magnets of CSNS/RCS is being developed. This pulsed power supply consists of IGBT H bridges in series and parallel. The pulse current of the prototype is 18000A, the voltage is about 3KV and the equivalent frequency is about 1MHz. This paper will introduce this prototype in detail.
SLAC, Menlo Park, California
ORNL, Oak Ridge, Tennessee
Funding: Work supported by the Department of Energy under contract No. DE-AC02-76SF00515.
The 1-MW High Voltage Converter Modulators* have operated in excess of 250,000 hours at the Spallation Neutron Source. Increased demands on the accelerator performance require increased modulator reliability. An effort is underway at SLAC National Accelerator Laboratory to redesign the modulator H-bridge switch plate with the goals of increasing reliability and performance**. The major difference between the SLAC design and the existing design is the use of press-pack IGBTs. Compared to other packaging options, these IGBTs have been shown to have increased performance in pulsed-power applications, have increased cooling capability, and do not fragment and disassemble during a fault event. An overview of the SLAC switch plate redesign is presented. Design steps including electrical modeling of the modulator and H-bridge, development of an integrated IGBT clamping mechanism, and heat sink performance validation are discussed. Experimental results will be presented comparing electrical performance of the SLAC switch plate to the existing switchplate under normal and fault conditions.
*W. A. Reass, et al., “Design, Status, and First Operations of the Spallation Neutron Source Polyphase
”, PAC, 2003
**M.A. Kemp, et al., “Next Generation IGBT Switch Plate
,” LINAC, 2008.
LANL, Los Alamos, New Mexico
NSTec, Los Alamos, New Mexico
Funding: Work supported by the United States Department of Energy, DOE contract Number: W-7405-ENG-36
Accurate and reliable beam position measurements are required to commission and operate the DARHT II Accelerator. The Beam Position Monitor (BPM) system developed for use on the DARHT II accelerator consists of 31 electro-magnetic detector assemblies, a computer network based data acquisition system, and custom analysis software. During an accelerator “shot”, each BPM uses arrays of b-dot detectors to intercept the electron beam’s changing magnetic field. Post shot analysis of the BPM data provides the beam current and position information used for steering and tuning subsequent shots. This paper will analyze the performance of the BPM system, now that several thousand beam shots have been achieved.