SRF2013 - List of Authors (Sawamura, M.)

Paper

Title

Page

Precise Measurement of Superconducting Cavity Movement in Cryomodule by the Position Monitor Using White Light Interferometer

291

H. Sakai, T. Aoto, K. Enami, T. Furuya, M. Sato, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
K. Hayashi, K. Kanzaki
Tokyo Seimitsu Co. Ltd, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

Alignment of Superconducting cavity is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to Liq He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL and successfully measured the displacement during 2K cooling with the resolution of 10 micron

TUP091

Field Emission Measure During cERL Main Linac Cryomodule High Power Test in KEK

678

E. Cenni
Sokendai, Ibaraki, Japan
K. Enami, T. Furuya, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

A compact Energy Recovery Linac (cERL) is under construction in KEK in order to proof the performance of the key components required for the future ERL project in KEK. The main linac L-band cavities were assembled and tested in the cryomodule under high power operation, during the test information concerning field emission were gathered by means of PIN diodes rings and NaI scintillator located at the cavities ends. The data were analyzed by means of simulations, taking into account the cavities operating conditions and interaction between the accelerated electrons and the cavity surface. The resulting information are used to deduce a possible emitter location, determining if there is any change in the cavities performance with respect to the last vertical test they undertook. With PIN diode is possible to observe the radiation pattern produced by field emission, inferring the meridian where the emitter belongs. On the other hand the bremsstrahlung spectra recorded with the scintillator allow an estimation of the cavity cell where the emitter is located.

THIOC02

High Power CW Tests of cERL Main-Linac Cryomodule

855

H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
E. Cenni
Sokendai, Ibaraki, Japan
M. Sawamura
JAEA, Ibaraki-ken, Japan

A main linac cryomodule have been constructed for Compact ERL project. It contains two 9-cell cavities, mounted with HOM absorbers and input couplers. After cavity string assembly, they were installed into the vacuum vessel of the cryomodule. It was placed inside radiation shield of cERL and connected to a refrigerator system. The cryomodule was successfully cooled down to 2K and low power and high power measurements were carried out.

Slides THIOC02 [12.842 MB]

THP068

New Design of HOM Coupler Using Coaxial-like Rounded Waveguide

1081

M. Sawamura
Japan Atomic Energy Agency (JAEA), Gamma-ray Non-Destructive Assay Research Group, Tokai-mura, Ibaraki-ken, Japan
R. Hajima, R. Nagai, N. Nishimori
JAEA, Ibaraki-ken, Japan

It is important to damp higher-order modes (HOMs) of superconducting accelerators especially for energy-recovery linacs of high current operation. Though various types of HOM couplers, beam line HOM dampers and waveguide HOM couplers have been developed, there are some problems such as inner conductor heating of output connector for HOM couplers and low packing factor for beam line HOM dampers. We propose new design of HOM coupler. This coupler consists of a coaxial line coupled with a cavity or a beam pipe and a rounded waveguide which cuts off the accelerating mode. The rounded waveguide is similar to a coaxial line and the inner conductor and outer conductor are connected with a plate which corresponds to waveguide side wall. This enables the inner connector cooled down efficiently through the outer conductor. The calculation results of MW-STUDIO will be presented.

Paper	Title	Page
MOP069	Precise Measurement of Superconducting Cavity Movement in Cryomodule by the Position Monitor Using White Light Interferometer	291
	H. Sakai, T. Aoto, K. Enami, T. Furuya, M. Sato, K. Shinoe, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan K. Hayashi, K. Kanzaki Tokyo Seimitsu Co. Ltd, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	Alignment of Superconducting cavity is one of the important issues for linear collider and/or future light source like ERL and X-FEL. To measure the cavity displacement under cooling to Liq He temperature more precisely, we newly developed the position monitor by using white light interferometer. This monitor is based on the measurement of the interference of light between the measurement target and the reference point. It can measure the position from the outside of the cryomodule. We applied this monitor to the main linac cryomodule of Compact ERL and successfully measured the displacement during 2K cooling with the resolution of 10 micron

TUP091	Field Emission Measure During cERL Main Linac Cryomodule High Power Test in KEK	678
	E. Cenni Sokendai, Ibaraki, Japan K. Enami, T. Furuya, H. Sakai, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	A compact Energy Recovery Linac (cERL) is under construction in KEK in order to proof the performance of the key components required for the future ERL project in KEK. The main linac L-band cavities were assembled and tested in the cryomodule under high power operation, during the test information concerning field emission were gathered by means of PIN diodes rings and NaI scintillator located at the cavities ends. The data were analyzed by means of simulations, taking into account the cavities operating conditions and interaction between the accelerated electrons and the cavity surface. The resulting information are used to deduce a possible emitter location, determining if there is any change in the cavities performance with respect to the last vertical test they undertook. With PIN diode is possible to observe the radiation pattern produced by field emission, inferring the meridian where the emitter belongs. On the other hand the bremsstrahlung spectra recorded with the scintillator allow an estimation of the cavity cell where the emitter is located.

THIOC02	High Power CW Tests of cERL Main-Linac Cryomodule	855
	H. Sakai, K. Enami, T. Furuya, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan E. Cenni Sokendai, Ibaraki, Japan M. Sawamura JAEA, Ibaraki-ken, Japan
	A main linac cryomodule have been constructed for Compact ERL project. It contains two 9-cell cavities, mounted with HOM absorbers and input couplers. After cavity string assembly, they were installed into the vacuum vessel of the cryomodule. It was placed inside radiation shield of cERL and connected to a refrigerator system. The cryomodule was successfully cooled down to 2K and low power and high power measurements were carried out.
	Slides THIOC02 [12.842 MB]

THP068	New Design of HOM Coupler Using Coaxial-like Rounded Waveguide	1081
	M. Sawamura Japan Atomic Energy Agency (JAEA), Gamma-ray Non-Destructive Assay Research Group, Tokai-mura, Ibaraki-ken, Japan R. Hajima, R. Nagai, N. Nishimori JAEA, Ibaraki-ken, Japan
	It is important to damp higher-order modes (HOMs) of superconducting accelerators especially for energy-recovery linacs of high current operation. Though various types of HOM couplers, beam line HOM dampers and waveguide HOM couplers have been developed, there are some problems such as inner conductor heating of output connector for HOM couplers and low packing factor for beam line HOM dampers. We propose new design of HOM coupler. This coupler consists of a coaxial line coupled with a cavity or a beam pipe and a rounded waveguide which cuts off the accelerating mode. The rounded waveguide is similar to a coaxial line and the inner conductor and outer conductor are connected with a plate which corresponds to waveguide side wall. This enables the inner connector cooled down efficiently through the outer conductor. The calculation results of MW-STUDIO will be presented.