ISIR, Osaka
* R. Kato et al, FEL’06, Berlin, Germany, August 2006, THPPH041, p.676, http://www.jacow.org.** J. Roensch et al, FEL’06, Berlin, Germany, August 2006, THPPH019, p.597, http://www.jacow.org
ISIR, Osaka
ISIR, Osaka
| Paper | Title | Page |
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| WEPPH029 | Development of the Longitudinal Phase-Space Monitor for the L-band Electron Linac at ISIR, Osaka University | 409 |
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The correlation between longitudinal positions of electrons in a bunch and their energies has a critical effect on the temporal evolution of SASE, and various methods are being developed to measure the longitudinal phase-space profile. We are developing a system to measure the longitudinal phase-space distribution of electrons by a combination of a bending magnet, a profile monitor, and a streak camera at the Institute of Scientific and Industrial Research (ISIR), Osaka University. In the preliminary experiments using a profile monitor utilizing optical transition radiation (OTR), it was confirmed that the monitor had higher momentum resolution than the presently used momentum analyzer consisting of a slit and a current meter*. However, we could not obtain the sufficient number of photons to obtain the phase-space image since, in addition to a low photon yield, the angular distribution of OTR emitted by the electron beam in the energy region of 10 – 20 MeV, with which THz-SASE and THz-FEL experiments are conducted at this laboratory, is too large to concentrate it efficiently on a streak camera. In order to increase the number of photons, we try to use silica aerogel as a radiator of the profile monitor by following the example of PITZ**. We will present an outline of the phase-space monitor we are developing and its experimental results.
* R. Kato et al, FEL’06, Berlin, Germany, August 2006, THPPH041, p.676, http://www.jacow.org.** J. Roensch et al, FEL’06, Berlin, Germany, August 2006, THPPH019, p.597, http://www.jacow.org |
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| WEPPH030 | Development of a Precise Timing System for the ISIR L-Band Linac at Osaka University | 413 |
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| We are developing a free electron laser (FEL) in the infrared region and also conducting SASE experiment in the same wavelength region using the L-band linear accelerator at the Institute of Scientific and Industrial Research (ISIR), Osaka University. In order to conduct such studies, stable operation of the linac is critical, so that we have developed a highly precise and flexible timing system for stable generation of the high intensity electron beam with the energy region of 10-30 MeV. In the timing system, a rubidium atomic clock producing 10 MHz rf signal is used as a time base for a synthesizer which is used as the master oscillator for generating the acceleration frequency of 1.3 GHz. The 1.3 GHz signal from the master oscillator is directly counted down to produce the clock signal of the timing system at 27 MHz and the four rf signals for the linac and laser used in the beam line. The start signal for the linac is precisely synchronized with the 27 MHz clock signal. To make an arbitrary delayed timing signal, a standard digital delay generator is used to make a gate signal for a GaAs rf switch, which slices out one of the 27 MHz clock pulses to generate the delayed timing signal. Any timing signal can be made at an interval of 37 ns and the timing jitter of the delayed signal is less than 2 ps (rms). We will report the new timing system and its performance in detail. | ||
| FRAAU04 | Re-Commissioning of the Far-Infrared Free Electron Laser for Stable and High Power Operation after the Renewal of the L-Band Linac at ISIR, Osaka University | 521 |
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| We have been developing a far-infrared FEL since late 1980s based on the 40 MeV, L-band electron linac at the Institute of Scientific and Industrial Research (ISIR), Osaka University. The first lasing was obtained at 32~40 um in 1994 and since then we progressively modified the FEL system and continued experiment in between to expand the wavelength region toward the longer wavelength. We finally obtained lasing at 150 um in 1998. We could not obtain power saturation because the macropulse duration is 2 us, though the RF pulse is 4 us long, due to a long filling time of the acceleration tube of the L-band linac and the number of amplification times is limited to 50 only. The linac was constructed approximately 30 years ago and it was not suitable for stable and high power operation of FEL, so that we suspended the development of the FEL. In 2002, we had an opportunity to remodel the linac largely for higher stability and reproducibility of operation. We also added a new operation mode for FEL in which the macropulse duration can be extended to 8 us. I took time to remodel the linac and commission it, but finally the operation mode for FEL is being commissioned and we are resuming the FEL again after the long suspension. We will report the progress and the current status of the re-commissioning of the FEL. | ||
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