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| TUPMA049 |
Development of an Injector to Generate a Very Short Bunch for a Super Coherent Terahertz Light Source Project
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178 |
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- T. Tanaka, K. Akiyama, H. Hama, F. Hinode, K. Kasamsook, M. Kawai, T. Muto, K. Nanbu, M. Yasuda
Tohoku University, School of Scinece, Sendai
- N. Kumagai, H. Tanaka
JASRI/SPring-8, Hyogo-ken
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A project to develop a coherent Terahertz (THz) light source is in progress at Laboratory of Nuclear Science, Tohoku University. The coherent synchrotron light in the THz region is emitted from electron bunches with a very short bunch less than 100 fs (rms) generated by a thermionic RF gun and a sophisticated bunch compressor. As an injector of this ring, we have developed an independently tunable cells (ITC) RF gun and a magnetic bunch compressor. The longitudinal phase space extracted from the ITC-RF gun can be manipulated by feeding RF microwave to cells independently. To generate a short bunch with a significant bunch charge, a magnetic compressor is used downstream from the gun. Two kinds of bunch compressors have been studied. From simulation of an injector, we have got a very short bunch length about 42 fs (rms). A prototype of the gun has been manufactured. Results of low power tests of the gun will be presented.
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| TUPMA052 |
Study on Compact DC Electron Gun using Single Crystal Cathode of LaB6
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181 |
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- K. Kasamsook, K. Akiyama, H. Hama, F. Hinode, M. Kawai, T. Muto, K. Nanbu, T. Tanaka, M. Yasuda
Tohoku University, School of Scinece, Sendai
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A novel, compact DC gun has been designed and is currently on a test bed at LNS. Applying 50 kV high voltage for the gun, it is expected to supply a high brightness beam of which the beam current of 300 mA and the variable pulse duration from 1 to 5 ?sec. In addition, a floating bias voltage can be applied between the cathode and the wehnelt to manipulate electric field near cathode surface. In order to produce lower emittance beam, the thermionic cathode should have very much higher current density and the size of that should be very small. Consequently we have chosen single crystal LaB6 as the thermionic cathode, which can provide higher current density with good homogeneity electron emission. The design parameters and initial operating experience of the DC gun are discussed. This DC gun will be used for free electron lasers such as backward-wave oscillator, advanced accelerator researches and other experiments. Results of numerical calculations show good distribution of macroparticles in the phase space, which results from optimization of the bias voltage. A normalized rms emittance at the exit of the gun is expected to be less than 1 ? mm mrad.
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| WEPMA038 |
A Study on the Applicability of Landau Cavity to the 1.2 GeV Booster Synchrotron at Tohoku University
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375 |
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- F. Hinode, K. Akiyama, K. Kasamsook, M. Kawai, A. Kurihara, T. Muto, K. Nanbu, Y. Shibasaki, S. Takahashi, T. Tanaka, M. Yasuda
Tohoku University, School of Scinece, Sendai
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In these years, a 1.2 GeV Stretcher-Booster (STB) ring at Laboratory of Nuclear Science, Tohoku University, has been mainly operated in the booster-storage mode in which the high energy gamma-ray beam generated via bremsstrahlung from internal target wire has been utilized for experiments of nuclear physics. Beam energy injected from linac is not high enough (150 or 200 MeV), so that radiation damping time is much long. Although the injector linac provides sufficient beam current without beam stacking, circulating beam current decays rapidly due to instabilities before the beam reaches the top energy. One of the main causes in the beam current limitation is supposed to be strong coupled bunch instability due to the cavity HOM. In order to suppress the instability, applicability of a third-harmonic Landau cavity has been studied for the STB. The 1.5 GHz Landau cavity was already manufactured and installed in the ring. Beam commissioning will be started soon. We are also planning to introduce a longitudinal feedback into the STB. We will report the present status of the STB in this conference.
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