FEL2014 - List of Authors (Washio, M.)

Paper

Title

Page

Longitudinal Diagnostics of RF Electron Gun using a 2-cell RF Deflector

929

M. Nishiyama, K. Sakaue, T. Takahashi, T. Toida, M. Washio
Waseda University, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

Funding: This work was supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.
We have been studying a compact electron accelerator based on an S-band Cs-Te photocathode rf electron gun at Waseda University. We are using this high quality electron bunch for many application researches. It is necessary to measure the bunch length and temporal distribution for evaluating application researches and for improving an rf gun itself. Thus we adopted the rf deflector system. It kicks the electron bunch with resonated rf electromagnetic field. Using this technique, the longitudinal distribution is mapped into the transverse space. The rf deflector has a 2-cell standing wave π-mode structure, operating in TM120 dipole mode at 2856 MHz. It provides a maximum vertical kick of 1.00MV with 750 kW input rf-power which is equivalent to the temporal resolution of around 58 femtoseconds bunch length. In this conference, we report the details of our rf deflector, the latest progress of longitudinal phase space diagnostics and future prospective.

FRA04

Optimization of High Average Power FEL Beam for EUV Lithography Application

990

A. Endo, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
H. Mizoguchi
Gigaphoton Inc, Hiratsuka, Kanagawa, Japan

Extreme Ultraviolet Lithography (EUVL) is realized with 100W plasma EUV source at 13.5nm. It is recommended by the EUVL community to evaluate an alternative approach based on high repetition rate FEL, to avoid the power limit of the plasma source. Several papers discuss on the possibility to realize superconducting FEL to generate multiple kW 13.5nm light. We must notice that the present SASE FEL pulse has higher beam fluence than the resist ablation threshold*, and high spatial coherence which results in speckle patterns, and random longitudinal mode beat which leads to high peak powerμspikes. An expanding mirror is installed after the undulator to reduce the beam fluence, external-seeding configuration is employed to reduce the longitudinal mode beat, and total reflection beam homogenizer is used for spatial mode mixing. Pulse repetition rate is more than 3MHz to cancel the speckle patter formation by averaging illumination. This paper discusses on the lowest risk approach to construct a prototype to demonstrate a high average power 13.5nm FEL for the best optimization in EUVL application, including the scaling to 6.7nm wavelength.
*J. Chalupský, L. Juha et.al, “Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids”, OPTICS EXPRESS 15, 6036 (2007)

Slides FRA04 [1.413 MB]

Paper	Title	Page
THP084	Longitudinal Diagnostics of RF Electron Gun using a 2-cell RF Deflector	929
	M. Nishiyama, K. Sakaue, T. Takahashi, T. Toida, M. Washio Waseda University, Tokyo, Japan T. Takatomi, J. Urakawa KEK, Ibaraki, Japan
	Funding: This work was supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT. We have been studying a compact electron accelerator based on an S-band Cs-Te photocathode rf electron gun at Waseda University. We are using this high quality electron bunch for many application researches. It is necessary to measure the bunch length and temporal distribution for evaluating application researches and for improving an rf gun itself. Thus we adopted the rf deflector system. It kicks the electron bunch with resonated rf electromagnetic field. Using this technique, the longitudinal distribution is mapped into the transverse space. The rf deflector has a 2-cell standing wave π-mode structure, operating in TM120 dipole mode at 2856 MHz. It provides a maximum vertical kick of 1.00MV with 750 kW input rf-power which is equivalent to the temporal resolution of around 58 femtoseconds bunch length. In this conference, we report the details of our rf deflector, the latest progress of longitudinal phase space diagnostics and future prospective.

FRA04	Optimization of High Average Power FEL Beam for EUV Lithography Application	990
	A. Endo, K. Sakaue, M. Washio Waseda University, Tokyo, Japan H. Mizoguchi Gigaphoton Inc, Hiratsuka, Kanagawa, Japan
	Extreme Ultraviolet Lithography (EUVL) is realized with 100W plasma EUV source at 13.5nm. It is recommended by the EUVL community to evaluate an alternative approach based on high repetition rate FEL, to avoid the power limit of the plasma source. Several papers discuss on the possibility to realize superconducting FEL to generate multiple kW 13.5nm light. We must notice that the present SASE FEL pulse has higher beam fluence than the resist ablation threshold, and high spatial coherence which results in speckle patterns, and random longitudinal mode beat which leads to high peak powerμspikes. An expanding mirror is installed after the undulator to reduce the beam fluence, external-seeding configuration is employed to reduce the longitudinal mode beat, and total reflection beam homogenizer is used for spatial mode mixing. Pulse repetition rate is more than 3MHz to cancel the speckle patter formation by averaging illumination. This paper discusses on the lowest risk approach to construct a prototype to demonstrate a high average power 13.5nm FEL for the best optimization in EUVL application, including the scaling to 6.7nm wavelength. J. Chalupský, L. Juha et.al, “Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids”, OPTICS EXPRESS 15, 6036 (2007)
	Slides FRA04 [1.413 MB]