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| MOPCH087 | Quasi-adiabatic Transition Crossing in the Hybrid Synchrotron | synchrotron, acceleration, proton, beam-losses | 234 | ||
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Non-adiabatic features around the transition energy are well-known to be one of most important beam physics issues in most of circular hadron accelerators. A novel technique to avoid them by the adiabatic motion, a quasi-adiabatic focusing-free transition crossing (QAFFTC), was proposed. In a longitudinally separated function-type accelerator*, in which particles are confined by an rf voltage or burrier voltages and accelerated by a step voltage, the confinement voltage can be arbitrarily manipulated as long as the particles do not diffuse, while a strict acceleration voltage is necessary for the orbit of a charged particle to be balanced in the radial direction. The introduction of QAFFTC is most suitable for the longitudinally separated function-type accelerator. This new method was examined in this type of accelerator**, both theoretically and experimentally. This was a first and significant application of the hybrid synchrotron. The results will be presented.
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*K. Takayama and J. Kishiro, Nucl. Inst. Meth. A 451, 304 (2000).**K. Takayama et al. Phys. Rev. Lett. 94, 144801 (2005). |
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| MOPCH119 | Present Status of the Induction Synchrotron Experiment in the KEK PS | acceleration, synchrotron, KEK, proton | 324 | ||
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A concept of the induction synchrotron, which was proposed by Takayama and Kishiro in 2000, has been demonstrated by using the KEK PS since 2004. A proton bunch trapped in the RF bucket was accelerated with the induction acceleration devices from 500 MeV to 8 GeV*, which was energized with the newly developed switching power supply. This form of the KEK PS is something like a hybrid synchrotron. In addition, the injected proton bunch was confined by the step barrier-voltages at the injection energy of 500MeV**, which were generated with the same induction acceleration device. Then a concept of the induction synchrotron that a proton bunch was captured by the barrier bucket and accelerated with the induction voltage is to be fully demonstrated.
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*K. Takayama et al. "Observation of the Acceleration of a Single Bunch by Using the Induction Device in the KEK Proton Synchrotron", Phys. Rev. Lett., 94, 144801 (2005).**K. Torikai et al. "Acceleration and Confinement of a Proton Bunch with the Induction Acceleration System in the KEK Proton Synchrotron", submitted to Phys. Rev. ST-AB (2005), KEK-Preprint 2005-80 A, December 2005. |
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| TUPCH067 | Time-resolved Beam Emittance Measurement of Dragon-I Linear Induction Accelerator | emittance, radiation, focusing, electron | 1166 | ||
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A beam emittance diagnostic system of an intense pulsed electron beam (20MeV, 2.6kA, 80ns) based on optical transition radiation is developed. A gated CCD camera is used to get time-resolved result. We develop a timing system to avoid the time jitter, an anti-interference system to avoid the electromagnetic interference, and a C++ code to deal with the experimental data. The measured emittance is about 2000¦Ð.mm.mrad, which is agree with the result of three gradient method.
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| WEPCH106 | Stationary Beam Electron Transport in AIRIX for the TRAJENV Code | electron, space-charge, focusing, target | 2161 | ||
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In the framework of the AIRIX program, the electron beam propagation between the injector and the X-conversion target is routinely simulated with the 2D TRAJENV code. We describe the physical models implemented in the code for a intense stationary beam. We present both the modeling of applied electromagnetic forces in induction cells and self generated ones. To avoid the cell damage due to target debris generated by the electron beam impact, a thin debris shield has been tested upstream the X-ray converter. Such a thin foil located in the beam pass, is taken into account in TRAJENV. We describe the modeling and the influence of the foil on the beam.
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| THPCH069 | BBU Calculations for Beam Stability Experiments on DARHT-2 | BBU, simulation, impedance, electron | 2943 | ||
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The DARHT-2 (Dual-Axis Radiographic Hydrodynamics Test) facility is expected to produce a 2-kA, 20-MeV, 2-microsecond flattop electron beam pulse. Normal operation requires that the beam exit the accelerator with a normalized transverse emittance of less than 0.15-cm-rad. The beam break up (BBU) instability is a potentially serious effect for a high current linear accelerator. It arises from the interaction between the beam and the cavity modes of the accelerating cells. In support of the beam stability experiments, simulations of BBU for DARHT-2 using the Lamda code have been carried out. The simulations used experimental data for the transverse impedance of the cells. Lamda was benchmarked against results calculated with the LLNL code BREAKUP. For nominal transport parameters, simulation results showed that the BBU growth was not significant in changing the beam spot. For a magnetic field reduced by a factor of 5, BBU growth was over a factor of 100, and the image displacement effect was significant.
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| THPCH070 | Long-pulse Beam Stability in the DARHT-II Linear-induction Accelerator | BBU, impedance, ion, vacuum | 2946 | ||
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The beam breakup instability has long been a problem for linear induction accelerators (LIAs). Although it is predicted to saturate in the strong focus regime relevant to LIAs most, if not all, LIAs have had pulse-widths too short to observe this effect. We recently completed BBU experiments on a 1.2 kA, 6.7-MeV configuration of the DARHT-II LIA having a 1600-ns pulse length much longer than the saturation time. The saturated growth observed in these experiments when we reduced the magnetic guide-field strength was in agreement with theory. We used these results to deduce that BBU growth will be insignificant in the final 2-kA, 17-MeV DARHT-II configuration with the tunes that will be used. Another problematic instability for long-pulse LIAs such as DARHT-II is the ion-hose. We also performed experiments with the 6.7-MeV long-pulse configuration of DARHT-II in which we deliberately induced ion-hose by raising the background pressure far above its normal value. The results of these experiments were used to show that ion-hose will not be a problem for to the final DARHT-II configuration.
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| THPCH094 | Fully Digitized Synchronizing and Orbit Feed-back Control System in the KEK Induction Synchrotron | controls, synchrotron, acceleration, KEK | 3012 | ||
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A concept of "Induction Synchrotron", where an extremely long bunch captured by the step barrier-voltages is accelerated with the induction accelerating voltage, is being to be fully demonstrated in the KEK 12GeV-PS for the first time*. Attractive applications of the induction synchrotron are such as higher intensity proton drivers, future high luminosity hadron colliders with superbunch, and arbitral-ion accelerators. Synchronization between the voltage-pulse generation and the beam circulation, accelerating voltage control, and beam-orbit control without beam-rf phase, which is analogous to Delta-R feedback in an RF synchrotron, are indispensable in the induction synchrotron. A fully digitized real-time pulse density and discrete timing control system with 1GHz DSPs has been newly developed. Notable characteristics of the control system, some of which are synchronization at 1MHz revolution frequency with 8ns timing accuracy, are explained in detail. Experimental results of the induction acceleration with the digital orbit controller are also presented in this paper.
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*K. Torikai et al. "Acceleration and Confinement of a Proton Bunch with the Induction Acceleration System in the KEK Proton Synchrotron", submitted to Phys.Rev.ST-AB(2005), KEK-Preprint 2005-80. |
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| THPCH120 | Development of a General Purpose Power System Control Board | controls, diagnostics, SLAC, impedance | 3083 | ||
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As high frequency switching solid state devices are replacing tube devices and linear devices, power systems become more compact and modular. In those systems, it is desirable to have a high quality and multi-function control board per each power system module. In order to maintain reliable operation of the power system module, the control board requires having multiple and complex functions. Moreover, the control board needs to be compact and low power consuming. It also needs to have a fast communication with the main control station. However, there is no such control board available commercially. Therefore, a general purpose power system control board (PSCB) has been under development since 2005 as a collaboration effort between PAL and SLAC. The PSCB is an embedded, interlock supervisory, diagnostic, timing, and set-point control board. It is designed to use in various power systems such as sequenced kicker pulsers, solid state RF modulators, simple DC magnet power supplies, etc. The PSCB has the Ethernet communication with the TCP/IP Modbus protocol. This paper will describe detail functions and preliminary test results of the PSCB.
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