Beam diagnostics control
for J-PARC LINAC
Guobao SHEN
J-PARC Center
Japan Atomic Energy Agency
Mar. 2008
Content
Overview of J-PARC LINAC
IOC Development
OPI Presentation
Beam Observation
Performance
Summary
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1. Overview of J-PARC LINAC
Major Parameters
Particles: H- (negative hydrogen)
Energy: 181 MeV, The last two SDTLs are debunchers
(400 MeV for ACS, 600 MeV for SCL)
Peak current: 30 mA (50 mA for 1MW at 3GeV)
Repetition: 25 Hz (additional 25 Hz for ADS application)
Pulse width: 0.5 msec
250m To RCS
Ion
(3.1m) (3.0m) (27.1m) (91.2m)(15.1m)(109.3m) L3BT
Source RFQ DTL SDTL ACS (58m)
To
(324MHz) (972MHz) SCC
ADS
50 keV 3 MeV 50.1 MeV 181(191)MeV 400 MeV
190.8 MeV 600 MeV
(400MeV) (600MeV )
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1. Overview of J-PARC LINAC
Beam diagnostics
Device Types Purpose Total
SCT (Slow Current Transformer) Beam Current 38
FCT (Fast Current Transformer) Beam Phase/Energy 61
Digital Switcher for phase detector Dynamic Range Change 21
BPM (Beam Position Monitor) Beam Orbit 102
WSM (Wire Scanner Monitor) Beam Size/Profile 36
BLM (Beam Loss Monitor) Beam Loss 58
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2. IOC Development
Hardware Interfaces of Monitor Control
WE modules from Yokogawa
Digitizer module for data acquisition
WE7118: 100MS/s, 14-bit resolution, 2 channels
for BPM, FCT & WSM
WE7111: 100MS/s, 8-bit resolution, 1 channel
for SCT and BLM
Digital switcher for phase detector
WE7262: DIO module
WER modules
Home-made Wave-Endless-Recorder.
200MS/s, 12-bit resolution, 4 channels
for BPM
10MS/s, 12-bit resolution, 4 channels
for BLM
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2. IOC Development
IOC for WE control
DAQ:
By IOC directly
IOC:
H/W: Advme7501 VME-SBC (PowerPC)
S/W: OS: vxWorks 5.5.1; EPICS: 3.14.8.2
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2. IOC Development
IOC for WER control
DAQ:
Rack-mounted Server: A Java based Application (METIS)
IOC:
H/W: Rack-mounted Server (Intel-based)
S/W: OS: RHEL 4 (Nahant); EPICS: 3.14.9
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3. OPI Presentation
Beam current
SCT waveform
MEDM based
Confirmed beam
1st day of 1st beam study
Beam current
EDM based
High intensity beam study
Confirmed beam @ 25mA
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3. OPI Presentation
Beam delivery
1st beam observation at 30º dump (RUN3 )
181MeV, 5.5mA, 20μs, 2.5Hz
30º dump
Bend
magnets
SCT 0º dump
beam
2mA
40s SCT Waveform
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3. OPI Presentation
Beam position
181MeV, 25mA
on May, 2007
Waveform (MEDM)
Orbit
(JCE Based)
JCE: J-PARC Commissioning Environment
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4. Beam Observation
BPM Monitor: Beam Position Stability
SDTL02BX May 24 SDTL03AX
Good position stability up to the SDTL-2 was performed, but positions were
moving after the SDTL-3 in 0.5-1 hour cycle.
We suspected a Q-magnet rare short, higher order mode in the cavity, etc., for
this instability.
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4. Beam Observation
Reason:
The frame of the wire scanner is
made of ceramics. Electrons
from the cavity charge up the
frame, and induced voltage
steers the beam.
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4. Beam Observation
BPM Monitor: Beam Position Stability
September 29
SDTL05A
After making new frame of the wire scanner, a clear beam orbit jump was not seen.
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4. Beam Observation
BPM Monitor: Beam position jitter RUN12
Vertical
Horizontal
Last 2 BPM’s in L3BT Last 2 BPM’s in L3BT
injection line injection line
2nd last BPM 2nd last BPM
Last BPM Last BPM
These 2 BPM’s are 4.1 m apart.
The position jitter at the RCS injection is around ±0.2 mm (60 m in
RMS) including the intrinsic jitter (or noise) of the monitor system.
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4. Beam Observation
Wire Scanner: Typical horizontal profile
25mA WS53 WS55
Collimator section
Slight halo
observed in
the horizontal
direction.
WS57 WS59
Slight halo
Noisy
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4. Beam Observation
Wire Scanner: Typical horizontal profile
25mA WS53 WS55
Collimator section
More profound
halo is observed
in the vertical WS57 WS59
direction.
Noisy
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5. IOC Performance
Resource using ratio (repetition: 2.5Hz)
CPU usage: < 40%
Memory usage: ~ 25%
During Beam commissioning
CPU Usage
Memory Usage
Performance
Repetition rate: up to 6Hz
Satisfy current requirement of beam commissioning (2.5~5Hz)
Achieved WE hardware limit
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6. Summary
Beam Diagnostics Control for J-PARC LINAC
Two type hardware interfaces are employed
Commercial hardware: WE from Yokogawa
Module based, Compact digitizer
Home-made digitizer: WER
EPICS based
IOC:
EPICS R3.14.8.2+vxWorks5.5.1
EPICS R3.14.9+RHEL 4
OPI
MEDM, EDM, JCE App
Effective beam commissioning
with the support of diagnostics control
The control of beam diagnostics proved their usefulness in
the beam status observation, and the beam commissioning
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