Superconducting accelerator Test Facility

STF

HOM BPM study at KEK-STF

H. Hayano, K. Watanabe* (KEK)

A.Kuramoto (Sokendai)

Superconducting accelerator Test Facility

STF

Contents

1. About STF accelerator 2. Example of Beam response 3. Conclusion

STF ATF

In KEK

Superconducting accelerator Test Facility

Generated X-ray

Capture cryomodule ( 2 cavities )

DRFS klystron Beam & Laser collision point

Beam dump

Photocathode RFgun

STF accelerator (1): QB

STF accelerator was built to from June 2011 to Feb 2012. Beam on (Under commissioning, Test working): to RF gun: Feb/2012 to beam dump: April/2012 The Beam operation will do until Nov 2012 for QB project.

Purpose: To demonstrate high brightness X-ray generation by inverse laser Compton scattering for Quantum Beam project supported by MEXT in Japan.

Superconducting accelerator Test Facility

STF

STF accelerator (2)

Optical cavity to create X-ray (Under preparing)

X-ray detector

Beam dump

Klystron (to drive capture module)

Capture Cryomodule (9-cell x 2) MHI-12: Max Eacc = 40 MV/m MHI-13: Max Eacc = 33 MV/m

Beam line

RF gun, Photo-Cathode, Gun Laser: in Tunnel Klystron to drive RF gun at ground

Beam parameter Pulse length: 1 ms Repetition rate: 5 Hz Charge：62 pC / Bunch Bunch Number : 162500 (162.5 MHz) Beam current : 10 mA Energy: 40 MeV

Superconducting accelerator Test Facility

STF

STF accelerator (3): STF Phase 2

2013: Install a 12 m cryomodule with 8 cavites.

2014: Beam operation will restart.

Superconducting accelerator Test Facility

STF

Beam Parameter

QB project STF Phase 2

Pulse length 1 ms 0.9 ms

Repetition rate 5 Hz 5 Hz

Bunch Spacing 6.15 ns (162.5 MHz) 369.27 ns (2.708 MHz)

Number of Bunch 162500 2437

Bunch Charge 62 pC 3.2 nC

Total charge / pluse 10,000 nC 7,798 nC

Beam Current 10 mA 8.7 mA

Bunch length 12 ps (Laser, FWHM) 10 ps (Laser, FWHM)

Max. Beam Enegry 40 MeV 21.5 MeV

Beam power 2.0 kW (40 MeV Beam) 0.8 kW (21.5 MeV Beam)

Q.B. : Number of bunch can change step by 4 bunches Multi-bunches operation is every time.

Superconducting accelerator Test Facility

STF

Beam operation (RF gun)

BMP-01

Laser Gate

30 ~ 40 pC / bunch 162450 bunches in 1ms rf pulse Beam Energy ~ 3 MeV

About 7 mA Beam generated form RF gun at March 2012. RF gun: 2.2 MW input (1050 us rf pulse)

Superconducting accelerator Test Facility

Beam operation to Beam Dump (1)

PRM-02 PRM-03 PRM-04 WM-PRM-05

* Image of profile monitor (QF01~QD04 off)

* Beam accelerates from ~ 4 MeV to 40 MeV by at Capture cryomodule.

* Beam size when pass at Capture cryomodule is < ¦ 1mm (circular beam)

Superconducting accelerator Test Facility

Beam operation to Beam Dump (2)

WM-PRM-05 PRM-08 WM-PRM-07 PRM-06

Beam profile at All magnet on.

Superconducting accelerator Test Facility

Beam operation to Beam Dump (3)

RF gun: 3.5MW, 250 us

Beam: 50 –57 pC / bunch

30000 bunches / pulse

Beam energy: 40 MeV

300 W beam power:

RF gun rf

Beam: 30000 bunches

184.5 us (30000 bunches)

50 pC

57 pC

Wall Current Monitor

Loss monitor

BPM-01

At 22 / June / 2012,

About 10 mA beam with 184.5 pulse width (30000 bunches in rf pulse) was accelerated to beam dump with small radiation loss.

This stable situation can keep during several hours.

Superconducting accelerator Test Facility

Beam size at collision point

Ãx：22.8 um

Ãy：21.3 um

Ãx：56.5 um

Ãy：52.6 um

RF gun 3.5 MW, SC cav 14.5 - 25.5 MV/m 40 MeV, 35 - 40 pC, 40 bunches Emittance : ~ 1.5 [mm mrad] at WM-PRM-05

Target Beam size (sigma)

= 10 ~ 20 um

At collision point (circular beam) Measured by wire scanner

Superconducting accelerator Test Facility

STF

Setup of HOM study: from May 2012

BPM will install at August 2012

1

4 3 2

Tektronix DPO7354

RF amp

High pass filter to reject TM010

80 mV/div,BW:3.5 G 500 ns/div,10.0 GS/s,IT,50.0 ps/pt

Digital Phosphor Oscilloscope

Beam: 90 pC/bunch 40 bunches in pulse

Superconducting accelerator Test Facility

STF

Example of Beam response (1)

Raw data of multi-bunch operation. Under analysis by A. Kuramoto.

Waveform taking by oscilloscope FFT analysis

Superconducting accelerator Test Facility

STF

Example of Beam response (2)

90 pC/bunch 40 bunch

TE111-2: High

TE111-3

To estimate a electrical center, we need to add an BMP after ST2-XY. Under analysis by A. Kuramoto.

HOM Signal respond by beam position.

Superconducting accelerator Test Facility

STF

Conclusion

The commissioning of beam operation of the STF accelerator was started from Feb 2012. The HOM BPM study was also started from May 2012. Now, a basic data of beam response is under taking, and preparing the hardware and software to estimate a electrical center of capture module.

Superconducting accelerator Test Facility

Collision point Mirror collision point

Optics of Quantum Beam Project

Beam size monitoring by tungsten wire scanner at both point

10 um beam size at collision point

Superconducting accelerator Test Facility

Date Normalized Emittance [mm mrad]

RF gun [MW]

SC cav. [MV/m]

Main Solenoid : Main/Backing

UV Laser Charge [pC]

Energy [MeV/C]

Vertical Horizontal

13/June 0.79 1.3 3.5 14.5, 24.0 306.23 / 100.73 Æ1mm 15-25 39.1

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