Global design analysis for highly repeatable solid-state klystron modulators

Abstract

This paper presents an analysis of the repeatability issue in the electrical-to-radio frequency conversion chains using pulsed klystrons. The focus is on the power electronics used in klystron modulators. Repeatability definition is presented and simulation results allow deriving important conclusions regarding the voltage repeatability harmonic content versus power electronics design directions. The trade-off between klystron modulator and low level RF controls is a key point for optimizing the global system repeatability performance. ABSTRACTThis paper presents an analysis of the repeatability issue in the electrical-to-radio frequency conversion chains using pulsed klystrons. The focus is on the power electronics used in klystron modulators. Repeatability definition is presented and simulation results allow deriving important conclusions regarding the voltage repeatability harmonic content versus power electronics design directions. The trade-off between klystron modulator and low level RF controls is a key point for optimizing the global system repeatability performance.

Control of an active bouncer for an ultra precise 140 μs-solid state modulator system

“…7, the waveforms are depicted. The measured values are compared to the calculated values according to (6)(7)(8)(9). They show high agreement with slightly lower values due to parasitic resistance, but V Bout, f in , which results in a higher voltage than predicted.…”

“…In order to derive the PR of a modulator system, the standard deviation σ t j of the flat-top voltage must be computed at any given point in time of the pulse. The highest standard deviation from all time samples σ t j,max must be considered [7]. Thereafter, the PR can be derived in dependence of the tolerance interval α.…”

“…The specified modulator repeatability must remain below 100 ppm. General methods determining the repeatability have been investigated in [6] and [7]. In this paper the repeatability of a modulator subsystem is derived by combining jitter measurements with a circuit simulation, so that a sensitivity analysis of the influencing factors, which are switching jitters and initial voltage distributions, can be performed.…”

“…Parameters for testing and comparison between measured values (Fig.7) and calculations according to(6)(7)(8)(9).…”

Novel active bouncer topology for klystron modulators based on pulsed transformers

“…Although the average losses during the pulse are higher on Topology #3 due to the operation of the power MOSFET in its linear region, the lower losses on the bouncer reset (output filter capacitor discharge between pulses) due to the absence of the damping branch (composed of C bd and R bd ), make this topology also the most efficient. In addition, the lower switching frequency harmonic content at the output makes possible to correct possible repeatability issues on the power system by means of a feedback loop on the low level RF control [9], in order to respect the challenging CLIC repeatability specifications (see Table 1). Therefore, topology #3 seems to be the most convenient one for the future CLIC klystron modulator active bouncer.…”