MOPVA073
Development of Peak-hold Module for Electron Emission in STF-Type Power Coupler for the ILC
Y. Yamamoto, E. Kako, T. Shishido (KEK, Tsukuba, Japan)
Abstract
The peak-hold module for the electron emission in the power coupler driven by the pulsed operation, like ILC (International Linear Collider) and E-XFEL, was developed in 2013.
This module can detect two kinds of signals. One is the peak height, and the other is the integrated charge in one pulse. During the RF conditioning for the STF-type power couplers,
installed into the STF-2 cryomodules, this module perfectly worked, and detected different trend between the peak height and the integrated charge. In this paper, the detailed result
for the peak-hold module is presented.
STF-type Power Coupler & Test Bench
Probe antenna for electron emission
Integration circuit module
 2 sets of power coupler per batch
 2 probe antennas for electron emission
 2 view ports for arc sensor
 Separated cold and warm vacuum
 2 directional couplers (Pfor, Pback)
Conditions for RF conditioning
downstream
Peak-hold module
Setup for RF conditioning
Ceramic window
View port for arc sensor
Insulation amplifier circuit module
Cold part
Warm part
Newly developed modules
upstream
 Travelling wave operation
 1.2 MW (pulse width < 500μsec)
 800 kW (pulse width > 500μsec)
 Repetition rate: 5Hz
 Pulse width: 10  30  100  500
 1500  1650μsec
 Insulation amplifier circuit module
 Isolating DC current
 Conversion from current to “amplified” voltage signal
 4 inputs/outputs
 Peak-hold module




Peak height detection within each pulse from 10μsec to 1650μsec
4 inputs/outputs
1 trigger input
Flexible timing delay
 Integration circuit module
Peak height detection by Peak-hold module
 Integrated charge detection within each pulse from 500μsec to 1650μsec
 4 inputs/outputs
 Flexible gate timing
Peak Height V.S. Integrated Charge
peak
500μsec of pulse width
peak
Chasing peak
Electron emission signals after insulation amplifier circuit module
Holding peak
Electron emission signal after peak-hold module
Other examples for peak detection
Although the two signals for the electron
emission had various trends in each power
level, the peak-hold module perfectly
detected every peak height.
Electron emission has…
 Dependence on power level
 Dependence on RF duty
1500μsec of pulse width
The both electron emissions are quite
different even for the same type of power
coupler.
Integration circuit + Peak-hold modules
After insulation amplifier circuit module
electron #1
electron #2
Forward power
After integration circuit module
After peak-hold module
saturated
 Peak-hold module has sharp response
 Integration circuit module has redundant response like “cold vacuum”
 Quite different trend between “electron #1” and “electron #2” in higher power level
Conclusion
The insulation amplifier circuit, the peak-hold, and the integration circuit modules were developed and tested in STF. These modules perfectly worked for the RF conditioning of
the STF-type power couplers installed into the STF-2 cryomodules. It was clear that there is the different trend between the peak height and the integrated charge. In future, the new
modules with 20 input/output channels will be developed for the STF-2 cryomodule operation.