| Paper | Title | Page |
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| TUPPH024 | Super Coherent THz Light Source Based on an Isochronous Ring with Very Short Electron Bunches | 371 |
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A project to develop a coherent Teraherz (THz) light has been progressed at Laboratory of Nuclear Science, Tohoku University. The coherent synchrotron light at the frequency region of THz is emitted from electron bunches of several tens femto-second bunch length created by a thermionic RF gun and a sophisticated bunch compressor. In addition, the beam is circulating a ring consisted of nearly complete isochronous optics for many turns*, so that the average power of the radiation may be considerably enhanced. Forgetting about the amount of the charge, thermionic RF gun is quite suitable to produce such a very short bunch. We have developed an ITC (Independently-Tunabel-Cells) RF gun**, which is consisted with two independent cavities in order to manipulate the longitudinal phase space. In addition to expected performance of the ITC RF gun and the bunch compressor, the paper describes the latest version of the lattice design of the isochronous ring and results of tracking simulations as well. Possibility of long wavelength SASE mode and superradiant on the isochronous ring are also discussed.
* H. Hama, Proc. the 27th Int. Free Electron Laser Conf., Stanford, CA (2005) 1-7. ** T. Tanaka, F. Hinode, M Kawai, A. Miyamoto, K. Shinto, H. Hama, Proc. PAC2005, Knoxville, TN (2005) 3499-3501. |
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| THPPH042 | A Compact Low Emittance DC Gun Employing Single Crystal Cathode of LaB6 | 680 |
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| Development of an electron gun capable of producing low emittance is in the interests of further applications of high brightness electron beam such as Smith-Purcell radiation for examples. A prominent point of this DC gun is that operation high voltage is very low and the emittance is, however, sufficiently low because of a short distance between the wehnelt and the anode. A pulsed high voltage of 50 kV is supplied, and pulse duration is variable from 1 to 5 sec. Since a higher beam current of the macropulse is required in general, a cathode should have higher current density, while the smaller size of the cathode is preferred for lower emittance. Consequently we have chosen single crystal LaB6 as the cathode, which can provide higher current with good homogeneity emission. In additon, a floating bias voltage can be applied between the cathode and the wehnelt to optimize the electric field for achieving the lowest emittance. Numerical calculations using EGUN shows a better normalized rms emittance is expected to be less than 5 mm mrad. A state-of-the-art electron source will possibly open new scientific opportunities in the many fields. |