Download Specifications of TESLA Modulator

Klystron Power Supplies for ILC
2nd Korean ILC Workshop
December 28-29, 2004
Pohang Accelerator Laboratory
Jong-Seok Oh
PAL/POSTECH
TESLA 500 RF Requirements
Specifications of the Power Supply
Power Requirements of the RF System
Peak RF power per RF station
9.7 MW
Duty cycle
0.685%
Average RF power available per RF station 66 kW
Klystron efficiency
65%
Modulator efficiency
85%
Total efficiency
55%
AC power per RF station
120 kW
Auxiliary power per RF station
14 kW
Total wall plug power per station
134 kW
Number of active stations
560
Total wall plug power
75MW
Layout of RF System
Overall Layout of the RF System
•
•
•
•
e-
572 (1144) klystrons in total
6 stations for two linacs
~100 (~200) modulators per station
12.5 MW ( 25MW) per station
e+
Principle of TESLA Modulator
• Pulse cable : 4 parallel, 6.45 Ohm, max. ~2.8 km
• Pulser unit : 2.8m(L) x 1.6m(W) x 2.0 m(H)
• Pulse transformer tank : 2m(L) x 1.2m(W) x 1.4m(H), 6.5 ton
TESLA Modulator Status
1. 10 Modulators have been built, 3 by FNAL and 7
by industry
2. 8 modulators are in operation
3. 10 years operation experience exists
4. Work towards a more cost efficient and compact
design has started
5. Many vendors for modulator components are
available
Long Pulse Modulator Options
Sine wave
Poor flat to ± 3.5% over 1.4 ms @ 50 Hz
5 times wasted power (4.6 MW peak power)
Hard tube
Large capacitor bank (0.5% droop  130 uF @140 kV  1.3 MJ)
High voltage series switch
PFN/Tr.
DTI
TESLA
SNS
0
1
Fixed pulse width, fast switching at moderate voltages
Large VxTp transformer
Series IGBT switch
No regulation possible
Complex voltage distribution and protection
Series IGBT switch + pulse transformer + bouncer circuit
Complex voltage distribution, Multiple switches, Large HV pulse
transformer
High frequency switching (20 kHz) by IGBT
Minimize series IGBT
Significantly reduced pulse transformer
No crowbar circuit needed
Specifications of TESLA and SNS Modulator
Parameters
TESLA I
TESLA II
SNS
Pulse width [ms]
2.0
1.4
1.4
Output voltage [kV]
130
110
140
Output current [A]
95
130
79
Repetition rate [pps]
10
10
60
12.35
14.3
11
Average power [kW]
247
200
924
Solid state switch
GTO
IGBT
IGBT
DC link voltage [kV]
10.6
10.6
 1.2
13
12
18
 0.5
 0.5
 0.5
86
89 (?)
> 93
RF Frequency [MHz]
1300
1300
805
Peak RF power [MW]
5
10
5
Peak power [MW]
Transformer step-up ratio
Flattop ripple [%]
Efficiency [%]
Features of SNS Modulator
AC power
3 phase SCR
voltage controller
DC storage
capacitor
IGBT switch +
H-bridge
Use industry standard 3 phase 13.8/2.1 kV 1.5MVA transformer
Dry type transformer with 5th and 7th harmonic traps
Coarse adjustment of DC voltage
Limit in-rush current at turn-on
Self-cleaning design
110 mF per polarity  160 kJ stored energy
Tradeoff between switching losses and size of magnetic device
20 kHz H-bridge in 3 phase
PWM to control and regulate output voltage
Bipolar switching to simply magnetic design
Switching losses of ~ 5 kW/device
1:18 voltage step-up with triple-resonant filter  1:47 voltage gain
Boost transformer +
Amorphous nano-crystalline cores with zero-magnetostiction
DC rectifier
Low stored energy in the output filter (2.25 J @ 140 kV)
19" control rack
Switchgear, SCR control head, power distribution panel, panel view
display, control chassis with IGBT gating, Interlock chassis, PLC
chassis
Pulse Waveform Comparison
SNS modulator
TESLA modulator
SNS Modulator Circuit
Converter Modulator Assembly
IGBT Mounting
Oil Pump /
Heat XChgR
HV Conn.
Output
Choke
Shunt
Capacitor
Low Inductance
Primary Bus
Output Diode Rectifier
Stepup XFMR
Experiences and Potentials of PAL (1)
PLS 200 MW Modulator
Max. Peak Power (MW)
200
Peak Output Voltage (kV)
400
Pulse Repetition Rate (Hz)
Operating
10
Max.
60
Equi. Pulse Width (ms)
7.5
Flat - top Pulse Width (ms)
4.4
PFN Impedance (W)
2.8
Input Voltage (V, 3f, 60Hz)
480
Experiences and Potentials of PAL (2)
Peak output power
Peak voltage
Peak current
Load impedance
Flat top width
HV pulse length
Pulse energy
Pulse repetition rate
Average output power
111 MW
350 kV
317 A
1104 W
2.5 ms
3.5 ms
389 J
100 pps
38.9 kW
C-band Smart Modulator No. 1
Summary
1.
2.
3.
4.
5.
6.
7.
8.
Bouncer modulator is a reasonable baseline design
Units have been tested over many years
Efficiency is ~ 86% and can be improved
Cost estimates 300k$ ~ 400k$ each for 576 units
Upgrades still being investigated
Other operating designs exist
New designs are also of interest
Charging supply technology and power distribution
are important issues
9. PAL has enough potential and experiences for ILC
modulator