Status of the 12GHz high power - PowerPoint Presentation

Slide1

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

Klystron

50MW

1500 ns

50 Hz

Test slot100 MW, 0 ... 350 ns

phase

modulation

hybrid

Modulator

pulse compression

CTF2

Klystron

Gallery

The goal:

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

Thermionic Gun

Future X Band cavity test

“With Beam”

LINAC

Delay Loop

Combiner Ring

CLEX Building

CTF2

Transfer Line TL1

Transfer Line TL2

Photo Injector

Test Area

X

band test area

System overview

Gallery

Bunker

LLRF

Interlocks

Vacuum

RF DAQ

Controls

Timing

Modulator

Waveguide network and pulse compressor

Rf

testing bunker

Rf

structure under test

Modulator

ScandiNova

solid-state modulator (Ser. #1)

f

or powering the XL5 klystron

Designed for 400kV, 300A, 3.25us HV pulse width FWHM, 1.5us RF pulse width at 50Hz repetition rateMax. 450kV, 350A, 3.5us, 50HzSpecified 0.25% HV ripple and 0.1% HV repeatability

Compact design (3x2m2) including HV oil tank and klystronPrimary voltage 1400V max.Integrated control and interlock systemIntegrated vacuum and solenoid power supplies for klystron

Klystron XL5 klystron, a scaled version of the successful XL4 klystron developed at SLACDelivers 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 SLACMore details in: SLAC-PUB-14377

Extraordinary robust, survived a vacuum leak, a gun realignment and an overheating solenoid without any performance decrease so far…

12GHz pulse compressor

Pulse compressor with temp. stabilization installed in test stand.

Pulse compressor WG components built by GYCOM, Russia.

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)

Q

loaded

=

2.375x10

4

,

Beta = 4.27, Q0 = 1.31x1055% power loss in compressorNeeds temperature stabilization better than 0.1KNeeds LLRF phase programmeNew design under production, see Igor’s posterOutput

Reflected

Waveguide networkCombination of rectangular and circular low loss waveguide network20% 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 bunkerCircular mode allows insertion of rf vacuum valve to isolate gallery waveguide network when changing structureTwo directional coupler for rf power production diagnosis and interlocking, three for structure tests before and after structure

Gallery

Bunker

Structure test bedRf 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 detectionSufficient space and flexibility to test e.g. two structure assemblies or structures in tanksThree-girder-design allows flexible replacement of diagnosticsDark- and breakdown current spectrometer planned to be installed end of 2012Proposal for dark current and breakdown current spectrometer currently under construction by Uppsala University, Sweden

LLRF and interlock systemLLRF system providing low- and medium power rf pulses for klystron driving and takes care of modulator-external interlockingLLRF 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 generatorFast rf data acquisition system for structure tests including diode and IQ power detection circuitsLocal 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 2012Waveguide network completed (including first structure under test and pulse comp.), measured and pumped downWaiting 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 has been conditioned with rf (directly into loads) up to 50MW, 300ns, 50Hz stable operation at 390kVKlystron U/I waveforms

Klystron breakdown event, FWD & REF power

Plans for start-upOnce hardware installation is done, testing will start up in the following orderCalibration 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 systemOperation of low power with tuned pulse compressor to check for performance and stabilityIf 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 operationTest 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

50 MW

6 MW

1GHz klystron area

Control room

Rack space

Storage space

~ 25 m

~ 30m

Most important components ordered or under tendering!

160 MW

160 MW

SummaryCERN 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:

For CERN

For YOU?