IPAC2013 - List of Authors (Kuramoto, A.)

Paper

Title

Page

Alignment Detection Study using Beam Induced HOM at STF

509

A. Kuramoto
Sokendai, Ibaraki, Japan
H. Hayano
KEK, Ibaraki, Japan

STF accelerator using L-band photocathode RF Gun and two superconducting cavities is under operation for R&D of ILC. Electron beam extracted from the RF Gun is accelerated to 40 MeV by two superconducting cavities. Cavity alignment requirements for ILC are less than 300um offset and 300urad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. We measured HOM signals to detect their tilt and bending. TE111-6 which has high impedance is used to estimate cavity offset. To find cavity tilt and bending, we selected pi over nine mode in the first dipole passband (TE111-1) and beam pipe modes. From information of TE111-1 which has maximum radial electric field in the middle cell, we can get electrical center of middle cell. At beam pipes, electrical center can be found by using beam pipe modes. Combinations of these electrical centers tell us cavity tilt and bending. We will present results of these TE111-1 and beam pipe mode together with beam trajectory information.

WEPME013

Development and Test of a Fully Automated PkQl Control Procedure at KEK STF

2950

M. Omet, A. Kuramoto
Sokendai, Ibaraki, Japan
H. Hayano, T. Matsumoto, S. Michizono
KEK, Ibaraki, Japan

In order to operate the cavities near their maximum gradients, cavity input (Pk) and cavity loaded Q (QL) should be controlled individually (PkQL control) at the International Linear Collider (ILC). A manual PkQL operation procedure was developed and performed at the linear electron accelerator at the Superconducting RF Test Facility (STF), in which the beam is accelerated up to 40 MeV by two superconducting 9-cell TESLA type L band cavities. The cavity gradients were set to 16 MV/m and 24 MV/m with QL values of 110⁶ and 3·10⁶. A 6.2 mA beam with a pulse length of 154 us was used. The field stabilities in amplitude were 0.160% and 0.097% for the cavities and 0.016% for the vector sum. The stabilities without beam are 0.057% and 0.054% for the cavities and 0.009% for the vector sum. For stability improvement during beam transient an adaptive beam feedforward for beam loading compensation is under development. So far an amplitude field stability of 0.013% for the vector sum was achieved at cavity gradients of 15 MV/m and 25 MV/m (no PkQL control) during a 6.8 mA beam with a pulse length of 123 us. Furthermore a fully automated PkQL control procedure is currently developed and tested.

Poster WEPME013 [0.647 MB]

Paper	Title	Page
MOPME019	Alignment Detection Study using Beam Induced HOM at STF	509
	A. Kuramoto Sokendai, Ibaraki, Japan H. Hayano KEK, Ibaraki, Japan
	STF accelerator using L-band photocathode RF Gun and two superconducting cavities is under operation for R&D of ILC. Electron beam extracted from the RF Gun is accelerated to 40 MeV by two superconducting cavities. Cavity alignment requirements for ILC are less than 300um offset and 300urad tilt with respect to cryomodule. It is necessary to measure their offset and tilt inside of cryomodule. Cavity offset has been already measured by using beam induced HOM at FLASH in DESY. Cavity deformation during assembly and by cooling contraction has not been examined yet. We measured HOM signals to detect their tilt and bending. TE111-6 which has high impedance is used to estimate cavity offset. To find cavity tilt and bending, we selected pi over nine mode in the first dipole passband (TE111-1) and beam pipe modes. From information of TE111-1 which has maximum radial electric field in the middle cell, we can get electrical center of middle cell. At beam pipes, electrical center can be found by using beam pipe modes. Combinations of these electrical centers tell us cavity tilt and bending. We will present results of these TE111-1 and beam pipe mode together with beam trajectory information.

WEPME013	Development and Test of a Fully Automated PkQl Control Procedure at KEK STF	2950
	M. Omet, A. Kuramoto Sokendai, Ibaraki, Japan H. Hayano, T. Matsumoto, S. Michizono KEK, Ibaraki, Japan
	In order to operate the cavities near their maximum gradients, cavity input (Pk) and cavity loaded Q (QL) should be controlled individually (PkQL control) at the International Linear Collider (ILC). A manual PkQL operation procedure was developed and performed at the linear electron accelerator at the Superconducting RF Test Facility (STF), in which the beam is accelerated up to 40 MeV by two superconducting 9-cell TESLA type L band cavities. The cavity gradients were set to 16 MV/m and 24 MV/m with QL values of 110⁶ and 3·10⁶. A 6.2 mA beam with a pulse length of 154 us was used. The field stabilities in amplitude were 0.160% and 0.097% for the cavities and 0.016% for the vector sum. The stabilities without beam are 0.057% and 0.054% for the cavities and 0.009% for the vector sum. For stability improvement during beam transient an adaptive beam feedforward for beam loading compensation is under development. So far an amplitude field stability of 0.013% for the vector sum was achieved at cavity gradients of 15 MV/m and 25 MV/m (no PkQL control) during a 6.8 mA beam with a pulse length of 123 us. Furthermore a fully automated PkQL control procedure is currently developed and tested.
	Poster WEPME013 [0.647 MB]