Transcript X-band-statusx

Status of the 12GHz high power rf
test stand at CERN
J. Kovermann, G. McMonagle, S. Doebert, N. Catalan-Lasheras, I. Syratchev, W. Wuensch,
G. Riddone, S.Curt, S. Rey, L. Timeo, E. Paju, K. Schirm, M. Naon (CERN)
F. Peauger, A. Hamdi (CEA Saclay)
D. Sprehn, J. Eichner, A. Haase (SLAC)
S. Kuzikov (IAP)
HG2012, KEK
Introduction
The goal:
Modulator
- X-band (11.99424GHz) test station for
testing accelerating structures and high
power rf components
- Delivers CLIC-style rf pulses up to
100MW peak, 250ns pulse length, 50Hz
rep. rate (100Hz after upgrade)
- Reliable, automatic operation 24/7
- Power source for other experiments like
beam loading tests using CTF beam
100 MW, 0 ... 350 ns
phase
CTF2
modulation
hybrid
Klystron
50MW
1500 ns
50 Hz
pulse compression
Delay Loop
Future X Band cavity test
“With Beam”
LINAC
Thermionic Gun
Test slot
Klystron
Gallery
Transfer Line TL1
Combiner Ring
CTF2
Photo Injector
Test Area
X band test
area
CLEX Building
Transfer Line TL2
System overview
-
LLRF
Interlocks
Vacuum
RF DAQ
Controls
Timing
Modulator
Waveguide network and pulse compressor
Gallery
Bunker
Rf structure under test
Rf testing bunker
Modulator
ScandiNova solid-state modulator (Ser. #1)
for powering the XL5 klystron
- Designed for 400kV, 300A, 3.25us HV
pulse width FWHM, 1.5us RF pulse
width at 50Hz repetition rate
- Max. 450kV, 350A, 3.5us, 50Hz
- Specified 0.25% HV ripple and 0.1% HV
repeatability
- Compact design (3x2m2) including HV oil
tank and klystron
- Primary voltage 1400V max.
- Integrated control and interlock system
- Integrated vacuum and solenoid power
supplies for klystron
Klystron
XL5 klystron, a scaled version of the
successful XL4 klystron developed at SLAC
- Delivers 50MW, 1.5us long rf pulses with
50Hz repetition rate at 400kV, 300A,
600W rf drive power
- Working frequency 11.99424GHz
- Five klystrons built by SLAC
- Conditioned and tested at SLAC
- Extraordinary robust, survived a vacuum
leak, a gun realignment and an
overheating solenoid without any
performance decrease so far…
More details in: SLAC-PUB-14377
12GHz pulse compressor
12GHz pulse compressor to compress 1500ns klystron output
pulse to 250ns long CLIC nominal pulse length
- Power gain of 2.82 calculated from rf performance
measured at low power after installation and tuning in
12GHz test stand (under vacuum)
- Qloaded = 2.375x104, Beta = 4.27, Q0 = 1.31x105
- 5% power loss in compressor
- Needs temperature stabilization better than 0.1K
- Needs LLRF phase programme
- New design under production, see Igor’s poster
Output
Pulse compressor with
temp. stabilization
installed in test stand.
Pulse compressor WG
components built by
GYCOM, Russia.
Reflected
Waveguide network
Combination of rectangular and circular low
loss waveguide network
- 20% rf power loss from klystron to structure
including pulse compressor
- 7m of circular overmoded, low loss
waveguide to connect rf power station with
structure under test in testing bunker
- Circular mode allows insertion of rf vacuum
valve to isolate gallery waveguide network
when changing structure
- Two directional coupler for rf power
production diagnosis and interlocking, three
for structure tests before and after structure
Gallery
Bunker
Structure test bed
Rf structure test bed allows rf testing of
different structure assemblies and provides
ports for breakdown diagnostics
- Designed to reach 100MW, 250ns rf
pulses with 50Hz repetition rate at the
input of the structure under test
- Vacuum chambers up- and downstream
of structure beam axis for pumping and
diagnostics, can be closed by valves
- Faraday cups at both ends of structure
for breakdown detection
- Sufficient space and flexibility to test e.g.
two structure assemblies or structures in
tanks
- Three-girder-design allows flexible
replacement of diagnostics
- Dark- and breakdown current
spectrometer planned to be installed end
of 2012
Proposal for dark current and breakdown current
spectrometer currently under construction by
Uppsala University, Sweden
LLRF and interlock system
LLRF system providing low- and medium
power rf pulses for klystron driving and takes
care of modulator-external interlocking
- LLRF chain with 12GHz synthesizer,
preamp with gating and TWT medium
power amplifier
- Timing and controls
- Rf and vacuum interlock PLCs
- Control of rf pulse compressor tuning
stepper motors and phase ramp function
generator
- Fast rf data acquisition system for
structure tests including diode and IQ
power detection circuits
Local control desk necessary for initial debugging and
conditioning. System is step by step integrated into CERN
controls environment.
NI PXI based system for operator support during
conditioning, keeps track of vacuum, temperatures, rf
waveforms etc. and performs basic conditioning
algorithms.
Status mid April 2012
- Waveguide network completed (including
first structure under test and pulse comp.),
measured and pumped down
- Waiting for vacuum IP power supplies and
control electronics to be installed
- Rf DAQ system needs to be finished and
calibrated
- HV flat top tuning by SC on-going
- New HV voltage divider and current
transformers installed in modulator
Klystron U/I waveforms
Klystron has been conditioned with rf
(directly into loads) up to 50MW, 300ns,
50Hz stable operation at 390kV
Output power [MW]
Gain curve for XL5 klystron
60.00
50.00
40.00
30.00
20.00
10.00
0.00
CERN
SLAC 400kV
SLAC 376kV
0
200
400
Drive power [W]
600
Klystron breakdown event, FWD & REF power
Plans for start-up
Once hardware installation is done, testing will
start up in the following order
- Calibration of all rf paths
- Another thorough check of all interlocks
- Rf production with detuned pulse compressor
 conditioning of rf network with 250ns rf
pulse width max.
- Testing of automatic structure conditioning
system
- Operation of low power with tuned pulse
compressor to check for performance and
stability
- If successful, condition pulse compressor and
waveguide network to nominal power in
parallel to a first structure test
- Implementation of controls and eventually
necessary hardware upgrades for routine
operation
- Test some structures…
Automatic conditioning and
structure test software
12GHz diode and IQ detector
replacement (log detectors, down
mixing) under development
Plans for future test stands
Most important components ordered or under tendering!
~ 30m
160 MW
6 MW
~ 25 m
50 MW
160 MW
1GHz klystron area
Control room
Rack space
Storage space
Summary
CERN x-band test stand will start testing CLIC structures this year!
Further test stands under preparation, klystrons ordered, modulators under
tendering.
And a message to our present and future collaborators: