Kyoto IAE, Kyoto
AET Japan, Inc., Kawasaki-City
A triode rf gun* is being developed, which is aimed at drastic reduction of electrons back-streaming and hitting the thermionic cathode. Thermionic rf guns in general show advantages over photocathode guns such as low cost, easy operation and high averaged current (high repetition rate), which are suitable for FELs for various uses. They however suffer from the electron back-bombardment resulting in limited macro-pulse duration of severalμseconds. In order to reduce the back-streaming electrons, the triode rf gun employs an rf cavity much shorter (e.g. ~2 mm) than the rf wavelength as the first cell with a thermionic cathode. The phase and amplitude of the rf field in the first short cell are then controlled independent from the successive cells. We have designed a triode rf gun and fabricated the additional short rf cavity which is to be installed in the S-band 4.5-cell rf gun used in the KU-FEL. The results from PIC simulations showed that the back-bombardment power is expected to reduce drastically by more than 80% without loss of beam brightness. Preliminary results from the cold testing and rf conditioning of the additional cavity will be also presented.
*K. Kanno et al., Japanese J. Applied Physics 41 (2002) 62-64, and
K. Masuda et al., Proc. of 27th Intnl. FEL Conf. 2005 (2006) 588.
Kyoto IAE, Kyoto
UVSOR, Okazaki
We proposed a table-top seeded THz FEL amplifier using a multi-bunch photocathode RF gun and injection-seeded terahertz parametric generator (IS-TPG) [1]. Although the first numerical study was carried out under simplified condition [2], a slippage effect, which has prominent effect to long wavelength FEL was not taken into account. In order to discuss feasibility and expected THz output power, start-to-end simulation of FEL was performed by simulation code Parmela [3] and 3D time-dependent FET simulation code GENESIS 1.3 [4]. The peak output power of about 10 kW at 185μm was expected from the design scheme.
[1] K. Kawase, et al., Applied Physic Letters 80(2002),p195
[2] T. Kii, et al., Proc. of FEL2008, in press.
[3] L.M. Young, et al., PARMELA, LA-UR-96-1835,(2001)
[4] S. Reiche, NIM A429(1999) p242.
Kyoto IAE, Kyoto
KAERI, Daejon
UVSOR, Okazaki
A mid-infrared free electron laser facility has been constructed for developing energy materials in Institute of Advanced Energy, Kyoto University. The accelerator has been installed and FEL gain saturation at 13.2 μm has been achieved in May 2008. The FEL power of about 3 MW has been observed at the accelerator room. We have constructed the FEL transport system from the accelerator room to the user room. The beam characterization at user room and preparation of the application of MIR-FEL will be introduced in the conference.
Kyoto IAE, Kyoto
UVSOR, Okazaki
A new type of undulator which consists of high-temperature superconductor bulk magnets in the staggered array configuration inside a solenoid is being developed, aimed at short period, high undulator field and controllability by the solenoid current.[1] In order to develop a numerical model, the field calculations were performed and comparisons were made with prototype measurements at the liquid nitrogen temperature. The field in the bulk magnet was modeled by loop currents of which amounts were determined by the critical current density which follow Bean model.[2] In the unsaturated condition, which is decided by the critical current density and the dimension of the bulk magnets, the field distributions and the dependence on the solenoid field were reproduced well. We then estimated the unsaturated performance at the liquid helium temperature, where increment of the critical current density is known [3] and significant improvement of the undulator performance is expected accordingly. In the conference, the experimental results, the detail of modeling and numerical results will be shown and also the performance estimation will be discussed.
[1] T. Kii, et al. FEL 2006, THPPH035 (2006),
R. Kinjo, et al., FEL 2008, THAAU03 (2008)
[2] C.P. Bean, Phys. Rev. Lett. 8, 250 (1962)
[3] M. Morita, et al. NIPPON STEEL TECHNICAL REPORT No. 93 (2006)
