AWA Facility Upgrade
Manoel Conde
(for the AWA group)
AWA Facility – Present: 15 MeV Drive Beam
Photocathode RF Gun:
• 1 ½ cell L-band (1.3 GHz)
• Magnesium photocathode (QE = 10-4)
• 80 MV/m on cathode surface
• 8 MeV, 1 – 100 nC (reached 150 nC)
• 2 mm bunch length
• emittance < 200 mm mrad (at 100 nC)
• High Current: ~ 10 kA
Bunch train operation:
Linac Structure:
• 4 bunches x 25 nC
• standing-wave π/2 mode L-band (1.3 GHz)
• 16 bunches x 5 nC
• 7 MV/m average accelerating gradient
• Large irises to minimize undesirable wakefields
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Motivation for AWA Upgrades
Restore two beam accelerator capability.
Have two parallel beamlines, allowing drive bunches to excite wakefields and
accelerate witness bunch.
Use the demonstrated high gradients to accelerate beam.
- The high quality drive beam has excited high gradient accelerating fields (100
MV/m) in dielectric loaded structures.
- Now these high gradients will be used to accelerate a witness bunch.
Higher drive beam energy is critical.
- Propagation of drive beam through smaller diameter structures, resulting in
even higher accelerating gradients.
- More energy available in drive bunches, allowing extraction of higher energy
RF pulses.
- Construction of longer structures will demonstrate higher energy gain.
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Overview of Proposed Upgrades
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Additional RF gun with Cesium Telluride photocathode (QE > 1%)
Six additional π mode linac tanks
Beam energy will increase to 75 MeV
Bunch train operation with 32 bunches x 60 nC (or 10 bunches x 100 nC)
Beam power of 5.9 GW (or 10 GW)
Witness beam to probe wakefields generated by drive beam
Beamline switchyard to allow concomitant experiments:
– collinear wakefield acceleration
– RF power generation and two beam acceleration
– phase space manipulation (emittance exchange, etc)
– high brightness beam generation
– beam diagnostic development
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New RF Gun with Cesium Telluride Photocathode
New RF gun installed in AWA bunker:
• 1 ½ cell, L band (1.3 GHz)
• 12 MW, 80 MV/m on cathode
• RF conditioned to 15 MW with Cu
photocathode
• First beam on 1/25/11
Cesium Telluride preparation chamber:
• necessary QE ~ 1%
• routinely achieving QE > 10%
• uniformity across ~ 25 mm diameter has
recently been improved
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New Linac Tanks
• 7 cell π mode, L band (1.3 GHz)
• 10 MW, 11.2 MeV energy gain
• Q = 26687
Shunt = 20.6 Mohm/m
R/Q = 773.4
• Under construction
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Additional RF Power
30 MW Litton klystron
on loan from LANL
(thanks to B. Carlsten
and S. Russell)
two new 25 MW klystrons have been delivered by
Thales
two new modulators
under construction
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New Beamlines
AWA Drive
Beam Out
75MeV
52MeV
AWA Drive Beam
30MeV
Two Beam
Acceleration
AWA Collinear
Wakefield and High
Brightness Beam
Emittance Exchange
and Beam Diagnostics
AWA Drive
Beam In
AWA Witness Beam & switchyard
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New Beamline Switchyard
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Collinear wakefield
acceleration
Drive Beam
Witness Beam
Drive Beam
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Two beam acceleration
Witness Beam
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Emittance exchange and
diagnostic development
Witness Beam
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Present AWA Bunker
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Building 366 Current AWA Bunker Configuration with Proposed Beamlines
Proposed AWA
Beamlines
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Proposed Bunker Expansion
63’
60’
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AWA - Building 366 Expansion
30’
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Goals to be Achieved with Upgrades
 In the past few years AWA has demonstrated high gradient fields (100
MV/m) in short dielectric based wakefield structures. Generation and
extraction of RF power using beam driven dielectric structures has also
been demonstrated.
 AWA is undergoing upgrades that will enhance its capabilities (new RF drive
gun, Cs2Te photocathode, higher beam energy). Once the upgrades are
completed, the goal is to achieve:
 Higher gradient excitation: ~ 0.5 GV/m in long structures ( 30 cm long,
3 mm apertures)
 Acceleration of witness beam: ~ 100 MeV
 Higher RF power extraction: ~ GW level (75 MeV, 78 Amps, 25 ns, 5.9
GW beam power)
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Timeline for Upgrades and Initial Experiments
 Start commissioning of Cs2Te photocathode in new RF gun: March 2011
 Complete two new modulators and install new klystrons: March - April
2011
 Receive first linac tank: May 2011
 Start bunker expansion: Spring 2011
 Receive remaining five linac tanks: Summer 2011
 Complete AWA bunker expansion: Spring 2012
 Initial experiments using new beamlines: Fall 2012
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