LINAC2014 - List of Authors (Ohshima, T.)

Paper	Title	Page
MOPP093	Evaluation of Beam Energy Fluctuations Caused by Phase Noises	273
	H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan T. Asaka, T. Ohshima RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP123	Development Activities of Accelerator Instruments for SACLA	342
	Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Ego, S. Matsubara JASRI/SPring-8, Hyogo, Japan
	The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.

Paper

Title

Page

Evaluation of Beam Energy Fluctuations Caused by Phase Noises

273

H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan
T. Asaka, T. Ohshima
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP123

Development Activities of Accelerator Instruments for SACLA

342

Y. Otake, T. Asaka, T. Inagaki, C. Kondo, H. Maesaka, T. Ohshima, T. Sakurai, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Ego, S. Matsubara
JASRI/SPring-8, Hyogo, Japan

The X-ray free-electron laser, SACLA, is constantly operated for user experiments aimed at new science. Experimental users demand further experimental abilities, such as many experimental chances by using multi-X-ray beam lines, much better repeatability of the experiment conditions and further intense high-energy X-rays. To equip SACLA with these abilities in the future, we have developed a 2pi /3 CG acceleration structure with an acceleration gradient of over 45 MV/m to adapt operation for generating the intense high-energy X-rays. A high-voltage power supply to charge the PFN of a modulator, a klystron and an acceleration structure were developed to adapt operation for 120 pps operation from the present 30 pps, since 120 pps is more suitable for beam distribution to the multi-beam lines. To meet the experimental repeatability realized by stable timing in a pump-probe experiment, an optical-fiber length control system to mitigate timing drift below 1 fs for 10 minutes was developed. Highly precise cavity temperature control system in an injector for below ±2mK was also realized. Performances of our developed instruments were experimentally tested to be sufficient for our demands.