Post on 03-Jul-2020
transcript
Status of the RF SystemS. Choroba, DESY
• XFEL RF Requirements• RF Station Layout• Status of the RF Components
– Klystron– Modulator– HV Pulse Cable– RF Waveguide Distribution
• Summary
XFEL RF RequirementsNumber of sc cavities: 960 total Power per cavity: 120 kWGradient at 20GeV: 23 MV/m Power per 32 cavities(4 cryo modules): 3.9MW Power per RF station: 5.2MW (including 10% losses in
waveguides and circulators and a regulation reserve of 15%)
Number of RF stations: 30 (27 active)Number of RF stations forinjectors: 5Macro beam pulse duration: 650µsRF pulse duration: 1.37msRepetition rate: 10Hz (50Hz) Average RF power per station: 71.2kW (150kW)
Layout of the RF-System
Multi Beam Klystron THALES TH1801 Measured performanceOperation Frequency: 1.3GHzCathode Voltage: 117kVBeam Current: 131ANumber of Beams: 7Cathode loading: 5.5A/cm2
Max. RF Peak Power: 10MWRF Pulse Duration: 1.5msRepetition Rate: 10HzRF Average Power: 150kWEfficiency: 65%Gain: 48.2dBSolenoid Power: 6kWLength: 2.5mLifetime: ~40000h
Multi Beam Klystron THALES TH1801 cont.
• 4 klystrons have been manufactured• The prototype PT has been in operation at TTF since May 2000
and has now 20000h operation hours• Series klystron #1 has been returned to the vendor after ca. 3000h
(gun arcing)• Series klystron #2 has been tested and returned to the vendor• Gun arcing has been investigated, the problem is identified and the
klystron has been modified• Modified klystron #1 has been sent back to DESY after successful
factory test and will be installed at TTF (if final test at DESY issuccessful)
• New klystron #3 is being tested at Thales and will be shipped to DESY in Zeuthen (if test is successful)
• More klystrons have been ordered
Multi Beam Klystron CPI VKL-8301
Design Features:•6 beams•HOM input and output cavity•Cathode loading: <2.5A/cm2
lifetime prediction: >100000h
Status:•Klystron has been succesfullytested at CPI in January 2005•Klystron is now at DESY and will be tested soon
The TOSHIBA E3736 MBKin cooperation with KEK
Design Features:•6 beams•Ring shaped cavities•Cathode loading: <2.1 A/cm2
Status:•Klystron has been testedsuccessfully up to 10MW peak, 1ms, 10Hz•Modulator needs modification foroperation at full pulse width•Test will continue at Toshiba in June/July 2005
Horizontal Klystron
• Next step: Modification towards a horizontal version• Horizontal klystrons are already in use e.g. the LEP
klystrons at CERN or the B-factory klytrons at SLAC• One vendor has already made a conceptual design of
a horizontal version• Final specification including all interfaces is pending,
prototypes must be built• Goal: test 2-3 horizontal prototypes within 2 years
Klystron Status Summary• Multi beam klystrons have been in use at TTF since
2000, gun arcing has been investigated, the problemhas been identified and modifications have beenmade
• 3 vendors have already manufactured or are near to manufacture klystrons meeting the XFEL klystronrequirements
• Lifetime of the klystron is expected to be >40000h limited by cathode lifetime, for cathode currentdensities <2.5A/cm2 the lifetime might be >100000h
• Specification, layout and construction for horizontal tunnel installation is pending
Modulators• Modulators must generate HV pulses up to 120kV
and 140A, 1.57ms pulse length and 10Hz (50Hz) repetition rate
• The top of the pulse must be flat within 1% • The bouncer type modulator with its simple circuit
diagram was chosen
The FNAL ModulatorWaveforms
•3 modulators have been developed, built and delivered to TTF by FNAL since 1994
•They are continuosly in operationunder different operation conditions
FNAL Modulator at TTF
Industry made Modulator
IGCT Stack
HVPS and Pulse Forming Unit•Industry made subunits (PPT, ABB, FUG, Beerwald)
•Constant power power supply forsuppression of 10Hz repetition rate disturbances in the mains
•Compact storage capacitor bankwith self healing capacitors
•IGCT Stack (ABB); 7 IGCTs in series, 2 are redundant
Industry made Modulator cont.•Low leakage inductance pulse transformer (ABB) L<200µH resulting in shorter HV pulse rise time of <200µs
•Light Triggered Thyristorcrowbar avoiding mercury of ignitrons
Pulse Transformer
KlystronVoltage 113kV
Klystron Current 132A
Modulator Status• 10 Modulators have been built, 3 by
FNAL and 7 together with industry
• 8 modulators are in operation
• 10 years operation experience exists
• Many vendors for modulatorcomponents are available
Modulator Status cont.Next Steps:
• Continue investigation of modulator operationat higher rep. rate up to 50Hz while keepingthe klystron average input power constant (at DESY Zeuthen)
• Write specification of modulator/pulse transformer for hall/tunnel installation(modular layout with low MTTR, higherMTBF, low EMI) and find vendors responsiblefor entire modulator
• Goal: test 2-3 full prototypes within 2 years
HV Pulse Cable• Transmission of HV pulses (10kV, 1.6kA, 1.57ms,
10Hz (50Hz)) from the pulse generating unit(modulator hall) to the pulse transformer (acceleratortunnel)
• Maximum length 1.5km
• Impedance of 25 Ohms (4 cable in parallel will give6.25 Ohms in total) to match the klystron impedance
• Triaxial construction (inner conductor at 10kV, middleconductor at 1kV, outer conductor at ground)
HV Pulse Cable cont.
diameter 30mmdielectric material: XLPE
HV Pulse Cable cont.
• Prototype cable has been delivered and and first test has been successful
• Experience with similiar cables in Europe and USA exists
• Minimum lifetime of the cables is 1010
pulses =111 years
HV Pulse Cable cont.
Klystron Voltage 128kVPrimary Current 1.1kA
Primary Voltage 10.6kV
Remaining problem: EMI needs investigation
RF Power Waveguide Distribution• Distribution of klystron output power to the
superconducting cavities• Protection of the klystron from reflected power• Control of phase and Qext
DETAIL
circulator
hybrid
loads
Q tuner
to cavity
RF from klystron
Cryomodule 1 Cryomodule 2 Cryomodule 3 Cryomodule 4
RF Waveguide ComponentsCirculator (Ferrite)3 Stub Tuner (IHEP, Bejing, China) E and H Bends (Spinner)
Type WFHI 3-4Peak input power, MW 0.4Average power, kW 8Min isolation at 1.3 GHz, dB >30Max insertion loss at 1.3 GHz, dB ≤0.08Input SWR at 1.3 GHz (for full reflection)
1.1
Type WFHL 3-1 WFHL 3-5Peak input power, MW 2.0 5.0Average power, kW 10 100Min return loss at 1.3 GHz, dB 32÷40 32÷40Max VSWR at 1.3 GHz <1.05 <1.05Max surface temperature, ∆T °C (for full average power)
20 30
Physical length, mm 385 850
Changing phase, degree 60Impedance matching range 1/3Zw 3ZwMax power, MW 2
* Zw – waveguide impedance
Directivity, dB 30Return loss, dB 35Coupling factor, dB(due to tolerance overlapping only 13 differentcoupling factors instead 18 are nessesary)
12.5; 12.0; 11.4;10.7; 10.1; 9.6;
9.1; 8.5; 7.8;7.0; 6.0; 4.8; 3.0
Accuracy of coupling factor, dB 0.2
Type WFHLL 3-1Peak input power, MW 1.0Average power, kW 0.2Min return loss at 1.3GHz, dB 32 40Max VSWR at 1.3 GHz 1.05Max surface temperature, T C (for full average power)
50
Physical length, mm 230
Hybrid Coupler (RFT, Spinner) RF Load (Ferrite)
RF Load (Ferrite)
RF Waveguide Distribution Status
• Waveguide components for the XFEL havebeen developed in cooperation with industryor are standard of the shelves components
• Operation experience of 10 years from TTF
• Development of integrated components has been started (e.g. circulator with integratedload) to allow faster and more reliableinstallation
Summary• For all RF system components vendors are available;
still need additional vendor for modulator• The HV pulse cable prototype has been
manufactured and tested• The problem of EMI needs further investigation• Industrialization process for the RF system
components is ongoing• Final design of XFEL versions of the RF system
components must be completed; but difficult to hiremore personnel