Transcript XFEL_RF_SYSTEM_B

XFEL/TESLA RF System Baseline
S. Choroba, DESY
• XFEL/TESLA RF Requirements
• RF Station Layout
• Status of the RF Components
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Klystron
Modulator
HV Pulse Cable
RF Waveguide Distribution
• Summary
• Possible KEK Support
XFEL/TESLA RF Requirements
Number of sc cavities:
Power per cavity:
Gradient at 500GeV:
Power per 32/36 cavities
(4/3 cryo modules):
Power per RF station:
Number of RF stations:
Macro beam pulse duration:
RF pulse duration:
Repetition rate:
Average RF power per station:
960/21000 total
122kW/231kW
17 .. 23.24MV/m/23.4MV/m
4.2MW/8.3MW
5.2MW/9.7MW (including 6%
losses in waveguides and
circulators and a regulation
reserve of 20%/10%)
35/572 incl. reserve and injectors
950ms
1.37ms
10Hz…50Hz/5Hz
250kW (400kW)/120kW
Layout of the XFEL/TESLA RFSystem
Multi Beam Klystron THALES TH1801
Measured performance
Operation Frequency:
Cathode Voltage:
Beam Current:
Number of Beams:
Cathode loading:
Max. RF Peak Power:
RF Pulse Duration:
Repetition Rate:
RF Average Power:
Efficiency:
Gain:
Solenoid Power:
Length:
Lifetime:
1.3GHz
117kV
131A
7
5.5A/cm2
10MW
1.5ms
10Hz
150kW
65%
48.2dB
6kW
2.5m
~40000h
Multi Beam Klystron THALES
TH1801 cont.
• 3 klystrons have been manufactured
• The prototype PT has been in operation at TTF since May
2000 and has now ca. 19000h 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 klystrons #1 and #2 have been tested at Thales
and will be tested at DESY soon. There are no hints of the
previous problem anymore.
• More klystrons have been ordered and will be delivered in 2005
Multi Beam Klystron CPI VKL-8301
Design Features:
•6 beams
•HOM input and output cavity
•Cathode loading: <2.5A/cm2
lifetime prediction: >100000h
Status:
•Bakeout in February 2004
•Test at CPI started March 22,
2004
CPI VKL-8301 cont.
• MBK has been tested untill June
2004
• has been conditioned to 120kV,
1.7ms, 10Hz in diode mode,
excellent beam transmission
• achieved 10MW with an
efficiency of 60% at an RF pulse
length of some 10ms
• while increasing the pulse length
to some 100ms a window problem
occurred at about 4-5MW
• the MBK has been removed from
test stand and has been opened,
the output window has been
modified
• Retested in Dec./Jan. 2005
• FAT passed Jan. 2005
• test at DESY spring this year
TOSHIBA E3736 MBK
in cooperation with KEK
Design Features:
•6 beams
•Ring shaped cavities
•Cathode loading: <2.1 A/cm2
Status:
•Bakeout April 2004
•Test started for July 2004
TOSHIBA E3763 cont.
• in August modulator
has been upgraded
• MBK has been
conditioned to 115kV,
1.5ms, 10Hz in diode
mode and has
excellent beam
transmission (>98%)
Cathode current (red) / collector
current (blue)
Cathode voltage (yellow):
Output of DC P/S
115kV
131 A
Cathode current (Green): output of
The IGBT switch
1.5ms
TOSHIBA E3763 cont.
•achieved 8.8MW at 1.3GHz and 9.5MW at 1.296GHz with 20ms
and 1Hz
•tuning of cavities was required;
•the klystron achieved 10.3MW at 40ms, 1Hz (Sept. 04)
•achieved: 10.3MW peak in 1ms long pulse at 10Hz (Nov. 04)
Main purpose of this tube: beam transmission test
Po (MW)
•FAT scheduled for May 2005
11
10
9
8
7
6
5
4
3
2
1
0
75kV
85kV
100kV
115kV
115kV
Cathode voltage (yellow):
Output of DC P/S
131 A
1.0ms
0
20
40
60
Pd (W)
80
100
120
RF Output (port A:
yelow , Port B: blue)
RF
drive
Horizontal Klystron
• Modification towards a horizontal version is
straightforward (no technological risks), but must be
done now for the XFEL
• Horizontal klystrons are already in use e.g. the LEP
klystrons at CERN or the B-factory klytrons at SLAC
• One vendor has already designed a horizontal version
Klystron Replacement
• the klystron lifetime will be determined by the cathode lifetime since
other klystron components are operated at a moderate level
•with a klystron lifetime of 40000h and an operation time of 5000h per
year 8 klystrons must be replaced during a monthly access day
•an overhead of 12 klystrons will be installed, therefore no degradation of
accelerator performance is expected between two access days
•teams of 3-4 people will exchange a klystron within a few hours;
klystrons will be equipped with connectors (HV, controls, cooling,
waveguides) which allow fast exchange of a klystron in the tunnel
Modulators
• Modulators must generate HV pulses up to 120kV
and 140A, 1.57ms pulse length and 5...50Hz
repetition rate
• The top of the pulse must be flat within 1%
• The bouncer type modulator with its simple circuit
diagram was chosen for TESLA and the XFEL
The FNAL Modulator
Waveforms
•3 modulators have been developed,
built and delivered to TTF by FNAL
since 1994
•They are continuosly in operation
under different operation conditions
FNAL Modulator at TTF
Industry made Modulator
PPT Modulator
•Industry made subunits (PPT,
ABB, FUG, Poynting)
HVPS and Pulse Forming Unit
•Constant power power supply for
suppression of 5Hz repetition rate
disturbances in the mains
•Compact storage capacitor bank
with self healing capacitors
•IGCT Stack (ABB); 7 IGCTs in
series, 2 are redundant
IGCT Stack
Industry made Modulator cont.
•Low leakage inductance pulse
transformer (ABB) L<200mH
resulting in shorter HV pulse
rise time of <200ms
Pulse
Transformer
•Light Triggered Thyristor
crowbar avoiding mercury of
ignitrons
Klystron
Voltage 113kV
Klystron Current 132A
Modulator Status
• 10 Modulators have been built, 3 by FNAL
and 7 by industry
• 8 modulators are in operation
• 10 years operation experience exists
• Many vendors for modulator components are
available
• Test at rep. rates up to 50Hz, keeping the
average power constant
• Work towards a more cost efficient, compact,
reliabale, modular design must be done now
HV Pulse Cable
• Transmission of HV pulses (10kV, 1.6kA, 1.57ms,
5..50Hz) from the pulse generating unit (modulator
hall) to the pulse transformer (accelerator tunnel)
• Maximum length 2.8km
• Impedance of 25 Ohms (4 cable in parallel will give
6.25 Ohms in total) to match the klystron impedance
• Triaxial construction (inner conductor at 10kV, middle
conductor at 1kV, outer conductor at ground)
HV Pulse Cable cont.
diameter 30mm
dielectric material: XLPE
HV Pulse Cable cont.
Primary Current 1.1kA
Klystron Voltage 128kV
Primary Voltage 10.6kV
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
Cryomodule 1
Cryomodule 2
Cryomodule 3
Hybrid C oupl er RF Distributi on
cavity i nput c oupler
waveguide
transformer
RF from Kl ystron
load
circulator
hybrid c oupler
DE TA IL
RF Waveguide Components
for operation with air
3 Stub Tuner (IHEP, Bejing, China)
Changing phase, degree
Impedance matching range
Max power, MW
Circulator (Ferrite)
E and H Bends (Spinner)
Type
Peak input power, MW
Average power, kW
Min isolation at 1.3 GHz, dB
Max insertion loss at 1.3 GHz, dB
Input SWR at 1.3 GHz
60
1/3Zw 3Zw
2
* Zw – waveguide impedance
WFHI 3-4
0.4
8
30
0.08
1.1
(for full reflection)
RF Load (Ferrite)
Hybrid Coupler (RFT, Spinner)
RF Load (Ferrite)
Directivity, dB
Return loss, dB
Coupling factor, dB
(due to tolerance overlapping only 13 different
coupling factors instead 18 are nessesary)
Accuracy of coupling factor, dB
30
35
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
0.2
Type
Peak input power, MW
Average power, kW
Min return loss at 1.3GHz, dB
Max VSWR at 1.3 GHz
Max surface temperature, T 
C
WFHLL 3-1
1.0
0.2
3240
1.05
50
(for full average power)
Physical length, mm
230
Type
Peak input power, MW
Average power, kW
Min return loss at 1.3 GHz, dB
Max VSWR at 1.3 GHz
Max surface temperature, T C
WFHL 3-1
2.0
10
3240
1.05
20
WFHL 3-5
5.0
100
3240
1.05
30
385
850
(for full average power)
Physical length, mm
RF Waveguide Distribution Status
• Waveguide components for TESLA and XFEL
have been developed in cooperation with
industry or are standard of the shelves
components
• Operation experience of 10 years from TTF
• Development of integrated components has
been started (e.g. circulator with integrated
load) and must be continued
• Development of a high power circulator for
operation with air and development of new
tuners have been started
Summary
• All main components for the XFEL RF system are
available today
• The HV pulse cable prototype has been
manufactured and test has been started
• For all components at least two vendors are available
and many components are standard catalog products
• Improvements for more cost efficient, enhanced
reliable and modular components must be done now
• Detailed layouts of all components for the XFEL are
required now.
Possible KEK support
• Continue support of Toshiba MBK
development (YongHo Chin, KEK)
• Accompany development of japanese
bouncer modulator ( e.g. visit of H.
Matsumoto, KEK and Choroba at
Nichicon in Kusatsu in Nov. 04)
• Support to qualify japanese waveguide
component vendors (Nihon Koshuha?)