| Paper | Title | Page |
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| THPPH035 | Design Study on High-Tc Superconducting Micro-Undulator | 653 |
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| A micro-undulator will be essential for compact and economical FEL systems. In this work, we introduce staggered array type micro-undulator using high Tc superconducting material. The high Tc superconducting material works as antiferromagnet pieces with pinning effect. Because a transverse magnetic field is potentially high, a micro-undulator with high K-value will be possible. Results of the field measurement with test pieces and estimated performance will be discussed in this conference. | ||
| THPPH036 | Design Study of RF Triode Structure for the KU-FEL Thermionic RF Gun | 656 |
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Thermionic rf guns show advantageous features compared with photocathode ones such as easy operation, low cost and high averaged current, which are suitable for their application to FELs for various uses. They however suffer from the back-bombardment effect, resulting in limited macro-pulse duration of severalμseconds. Against this adverse effect, we plan to introduce the triode structure*,** in the 4.5-cell rf gun for the KU-FEL by replacing the thermionic cathode by an assembly of a cathode with an additional coaxial cavity. Two-dimensional simulations have predicted a significant reduction of the back-bombardment power by 99% with a moderate rf power of several tens kW fed to the additional extraction cavity. Moreover an improved energy spread and peak current are expected at the same time with an optimal geometry and operating conditions.
* E. Tanabe et al., Proc. of 27th Linear Accelerator Meeting in Japan (2002) 57, in Japanese. ** K. Masuda et al., Proc. of 27th Intnl. FEL Conf. 2005 (2006) 588. |
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| THPPH037 | Magnetic Field Measurement of the Undulator in KU-FEL | 660 |
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We have constructed an infrared FEL facility for advanced energy researches. In the last FEL conference, numerical studies on the undulator in KU-FEL by optimizing both for electron beam and for the optical cavity have been presented*. On the other hand, since the undulator had been used in FELI**, demagnetization has been anticipated. So we have measured the magnetic field of the undulator. In this conference, we will show the FEL gain and the spectrum of spontaneous emission by using the measurement data.
* T. Fukui, et al., Proc. of the 2005 FEL conference (2005) 195-198. ** E. Nishimura, et al., Nucl. Instr. and Methods, A341 (1994) 39-42. |
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| THPPH038 | Production of Electron Beam with Constant Energy by Controlling Input Power into a Thermionic RF Gun | 664 |
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| We have studied on performance of a thermionic RF gun. Though a thermionic RF gun is a compact and economical electron gun, a backbombardment effect makes it difficult to produce electron beam with constant energy. The backbombardment effect depends on cavity voltage of the RF gun (Vc) and cathode current density (Jc). We tried to keep beam energy constant in macro pulse duration by feeding modulated RF power in experiment. We have succeeded to produce a 4 μs macro pulse electron beam. We also tried to perform transient analysis with equivalent circuit including the time evolution of beam loading depending on the Vc and Jc, By using this analysis we have succeeded to reproduce the measured time evolution of electron beam energy and the pulse shape of reflected RF power in case a constant RF power was fed and a modulated RF power was fed. Moreover we found the condition in which we could produce a 6 μs macro pulse electron beam. In this conference we will discuss the comparison between the experimental results and the calculation results. | ||
| THPPH039 | Experimental Study on Effect of Energy Distribution on Transverse Phase Space Tomography | 668 |
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Tomographic method * using a quadrupole magnet and a beam profile monitor is useful method of transverse phase space measurement. However the method is suffered from energy distribution. Therefore we have evaluated the effects numerically. As the result, the low energy tail of the beam distorted the result of tomographic method even with a small amount of the tail **.To confirm the numerical evaluation, measurements have been performed with single slit method, whose result is free from energy distribution. In this conference, the experimental result of two methods will be shown and a new tomographic analysis, which mitigates the effect of energy distribution, is proposed.
* C. B.McKee, et al, NIM A 358 (1995) 264** H. Zen, et al, Proc. of FEL2005 (2006) 592 |