IUCF Technical Note
Title:
ALPHA project commissioning plan
Doc Number:
Author:
V. Anferov
Date:
February 14, 2009
Version:
1.1
ALPHA Project Commissioning Plan
for Phase I and II
1. Purpose
This document outlines ALPHA project development phases and describes commissioning activities
for each development phase. The beam commissioning tests in turn define specifications for the
beam diagnostics needed to carry out specific measurements.
2. Project Phases and goals
Phase
Name
Goals
I
Medical Linac development
II
Ring Development
III
High Power Linac
Commission medical linac and develop single pass
through the storage ring.
Develop beam accumulation and acceleration in the
storage ring
Design and development of the high power electron
radiation test facility with Compton backscattering
production capability
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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3. Phase I: Medical Linac commissioning
Major Goals: Test Medical Linac performance, design Linac beam matching to the storage ring.
Medical Linac will operate at single (maximum) energy and will have manual controls only for
the pulse duration, pulse height, and pulse rep rate.
Anticipated Medical Linac beam properties:
Beam Energy
Bunch length
Bunch rep rate
Bunch charge
Ave. Beam current
Macro pulse length
Beam power per pulse
Beam energy spread
22 MeV
10−35 psec
2.87 GHz (0.35 nsec)
0.03 nC
80mA
0.02 to 2 sec
3.5 Joules
5−10%
Linac Commissioning Setup:
1. Medical Linac manually configured to deliver either short or long beam pulses.
2. Short beam line under 10−9 Torr vacuum.
3. The beam line includes calibrated quadrupole magnet and a 90-deg bending magnet (or a
doublet of 45-deg bending magnets);
4. A water cooled momentum selection slit with beam current readout capability on each jaw.
5. Wire Harp with 32 wires in horizontal and vertical planes spaced at 1mm apart.
The Wire Harp must be installed in vacuum at about 50cm distance from the quadrupole.
6. Wide band (3GHz) wall gap monitor or fast beam current transformer.
7. Small beam dump (made of Aluminum) and local shielding (lead bricks).
Task I.A: Develop and measure Linac pulse length in two modes of operation:
a) Long pulse mode
1.0 to 2.0 sec;
b) Short pulse mode
0.05 to 0.5 sec.
Required beam diagnostics:
a) Wide band in flange beam current transformer or Wall gap monitor (3GHz)
b) Oscilloscope (3 GHz)
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
2
Task I.B: Measure Linac pulse height.
Establish Min/Max intensity for Long and Short beam pulses.
Required beam diagnostics:
a) Wide band in flange beam current transformer or Wall gap monitor (3GHz)
b) Oscilloscope (3GHz)
Task I.C: Measure beam energy (energy spread) from the Medical Linac
a) Measure Max/Min beam energy for short pulses;
b) Compare the beam momentum spread with ring acceptance of ±1%
c) Measure Max/Min beam energy for long pulses;
d) Compare the beam momentum spread with ring acceptance of ±1%
Execution Plan: Once the accelerator is setup to deliver maximum energy, the beam is transmitted
through the momentum selection system of two 45-deg dipoles and horizontal slit. The
width of the slit must be set to 0.02×Dx= 0.02××(1−cos(bend)) which corresponds to ±1%
momentum acceptance of the ring. Once the transmission through the slit is maximized, the
dipole magnet current defines the beam energy. To measure the energy spread, vary the
dipole strength until the beam is removed from left jaw while right jaw sees majority of the
beam. Repeat the measurement for the right jaw and the two settings of the dipole magnets
define spectrum of energies accelerated in the medical Linac.
Required beam diagnostics:
a) Field mapped doublet of 45-deg bending magnets;
b) Water cooled slit with current readout from each jaw and opening width set to match CIS
energy acceptance of ±1%.
c) (Optional) Faraday cup or Wall gap monitor behind the slit to measure / optimize beam
intensity distribution over the energy spectrum.
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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Task I.D: Measure beam emittance
Execution Plan:
Setup Medical Linac to deliver short beam pulses;
The 90-deg momentum selection system is set for optimum high energy beam transmission.
With quadrupole magnet setup for vertical focusing vary the quadrupole strength to observe
a focused beam on a wire harp. Vary the quadrupole strength and record the beam spot size
on the wire harp going through a minimum. Change the quadrupole polarity and repeat the
measurement for the horizontal plane
Required beam diagnostics:
a) Wire harp with 1mm spacing (32 horizontal and 32 vertical wires);
b) Harp readout electronics (4 MCGI cards)
c) Calibrated PS with 15bit control and readout connected to a quadrupole with known field
map.
Task I.E: Optical matching of the Medical Linac to the Storage Ring
Execution Plan:
Based on the Medical Linac emittance measurements calculate the quadrupole triplet settings
for optical matching of the linac beam to the Storage ring. Validate polarity of all magnets.
Required components:
a) A set of three or four Quadrupole magnets installed in the Linac-to-CIS transfer line.
b) Each magnet refurbished, aligned and checked with a portable hall probe.
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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4. Phase II: Storage Ring commissioning
Major Goals: Develop Linac pulse stretching for single turn through the ring operation, develop
multi-turn accumulation in the storage ring, develop nonlinear beam transport (including
octupoles) from the ring to the test, beam acceleration development (optional).
Anticipated Storage Ring beam properties:
Beam Energy
Circumference
Revolution frequency
Dipole bend radius
Beam dumping time
Betatron tunes
Beam Life time
20 MeV to 125 MeV
20 m
14.9896 MHz (66.7 nsec)
1.273 m
~60 s at 25MeV (~10 s at 50MeV)
Qz=0.77; Qx=1.75
~60min
Commissioning Setup:
1. Medical Linac configured to deliver either short or long beam pulses synchronized to the
storage ring trigger/timing system.
2. Linac to Ring injection beam line under 10−9 Torr vacuum with capacitive pickup and strip
line BPMs.
3. Extraction beam line under 10−9 Torr vacuum with capacitive pickup or wall gap monitor
and strip line BPMs.
4. Storage ring with .
5. Wide band (3GHz) wall gap monitor or fast beam current transformer.
6. Small beam dump (made of Aluminum) and local shielding (lead bricks).
Preconditions:
o Shielding barriers are installed
o Room safety interlock system is tested
o Radiation monitoring system is installed?
o Magnet safety interlocks are tested (temperature and water)
o Polarity of all magnets in the ring and beam transport system is tested
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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Task II.A: Development of a Single turn through the ring
Note: Beam losses are anticipated during initial development of the beam injection. Simple beam
loss monitoring system may prove usefull.
Execution Plan:
Setup Medical Linac to deliver low intensity short beam pulses. Use the wire harp in the ring to
transport the beam to half turn location. Optimize Lambertson magnet setting to eliminate any
vertical offsets. Generate an orbit bump near the Lambertson magnet using the trim windings
on the adjacent dipoles. Observe beam extraction through the Lambertson magnet.
Required components:
a) Ring vacuum system with vacuum quality of at least 109 torr.
b) Control system must be able to set and read back the setting of each magnet.
c) Wire Harp at half-turn location of the ring.
d) Strip line BPMs in the injection beam line to center the injected beam. Movable harp or
scintillator screen can be used instead.
e) Faraday cup in the extracted beam line to measure extracted beam intensity.
Task II.B: Measure extracted beam RF structure
Execution Plan:
Setup Medical Linac to deliver long beam pulses. With ring setup for single turn transmission
observe the RF structure of the beam in the injection beam line and extraction beam line using
wide band wall gap monitor or capacitive pickups. Perform similar measurements at different
settings of the damping wigglers, which would change the orbit compaction from negative
(0.8) to positive (+0.2) in steps of 0.2.
Required components:
a) Capacitive pickups and /or Wall Gap monitor to observe beam RF structure.
b) 3GHz scope.
c) Faraday cup in the extracted beam line to measure extracted beam intensity.
d) Damping wigglers installed in the ring (with prior magnetic mapping and testing)
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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Task II.C: Develop multi-turn beam accumulation
Execution Plan:
Install electrostatic kickers into the ring. Develop accumulation of four turns at a single
kicker voltage. Develop kicker ramp profile for accumulation of 10 turns at multiple kicker
voltages.
Required Components:
a) Two electrostatic kickers with programmable ramp profile.
b) Wide band in flange Current Transformer/Wall Gap monitor for beam transmission /
accumulation measurements.
c) Ring BPM system for observing beam oscillation around closed orbit.
d) Dumping wigglers for horizontal beam stability
e) Timing system for triggering Linac pulses and kicker ramping
Task II.D: Develop beam acceleration
Note: The maximum energy of the accelerated beam may be limited by the capability of the kicker
system, but could reach 125MeV otherwise.
Execution Plan:
Install 15MHz RF cavity. Setup accumulation of four turns at a single kicker voltage.
Develop RF voltage and ring magnets ramp profile for beam acceleration to 50MeV.
Required Components:
a) 15MHz RF cavity with RF voltage and phase control.
b) Timing system to trigger magnet ramping.
c) Dumping wigglers for horizontal beam stability (ramped along with main dipoles)
d) Ring BPM system for beam position observation during ramp.
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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Task II.E: Investigate optimum beam damping conditions
Execution Plan:
Investigate beam dumping at various settings of the damping wigglers.
Required Components:
a) Dumping wigglers for horizontal beam stability.
b) Ring BPM system for beam position observation.
c) 15MHz RF cavity for fixed energy operation.
d) Wall gap monitor?
5. Summary on the beam diagnostics required for Phase I
Diagnostic Elements
Features
Manufacturer
In flange current transformer
(Beam current measurement)
Bandwidth: 1kHz850MHz,
Low droop (<1%/msec);
High vacuum enclosure
1mm spacing
32 horizontal +32 vertical wires
CIS vacuum enclosure
Bandwidth > 3GHz,
3GHz scope for readout
Bergoz;
PN: FCT-122-LD-20:1 in 6.75”
Conflate Flange
IUCF
Bandwidth > 3GHz,
3GHz scope for readout
IUCF?
Wire harp
(Beam profile measurement)
Wall gap monitor
(Beam current and RF structure
measurements)
Capacitive pickups
(RF structure measurements)
Fermilab?
ALPHA Commissioning plan
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Technology Center. Unauthorized reproduction of these documents is prohibited.
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Figure 1: Capacitive 50 Ω pickup for wide band bunch structure measurements.
Figure 2: Schematic view of a wall gap monitor.
ALPHA Commissioning plan
All intellectual property and other rights in this material are owned by the Indiana University Research and
Technology Center. Unauthorized reproduction of these documents is prohibited.
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