A Pulse Power Modulator with Extremely Flat-top Output Pulses for the Compact Linear Collider at CERN

Janne Holma

Research output: ThesisDoctoral ThesisMonograph


This dissertation presents the design procedure and results of measurements on two prototypes for a high-stability pulse power modulator. Design and prototyping of the pulse modulator is a part of the feasibility study of Compact Linear Collider (CLIC) study. The CLIC design relies on Pre-Damping Rings (PDR) and Damping Rings (DR) to achieve the very low emittance through synchrotron radiation. The pulse power modulators for the DR kickers must provide extremely flat, high-voltage pulses. The final specifications of the 2 GHz baseline called for a 160 ns duration flat-top of 12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 % of the output voltage, corresponding to ±2.5 V of absolute accuracy. The dissertation begins with a literature review to choose the topology for a high-precision pulse power modulator. A modulator based on solid-state switches, the inductive adder, has been selected as the most promising approach to meeting the specifications. This topology allows the use of both digital and analogue modulation techniques. Then, the electrical and mechanical design of the inductive adder are presented, especially for matching the output impedance of the modulator to a load. The reasoning for selecting the main components for an inductive adder is also covered. Simulation studies of applying different compensation methods for achieving the required pulse waveform for the CLIC DR extraction kicker system are also presented. Two prototype inductive adders were built to verify these methods experimentally. Finally, a design proposal is presented for a 12.5 kV inductive adder covering main components and preliminary simulation results. As the main results, the dissertation presents experimental verification of applying modulation methods to improve the pulse flat-top stability of a high-voltage pulse power modulator. These measurement were done with two built prototype inductive adders. The best measured relative accuracy for the pulse flat-top stability was ±0.05 % at 1.8 kV for 160 ns pulse flat-top duration, which corresponds to ±1 V of absolute accuracy. The dissertation shows that the required high stability for the CLIC DR extraction kicker inductive adder is very probably feasible with the developed design.
Translated title of the contributionÄärimmäisen tasalatvaisia pulsseja tuottava pulssiteholähde CERNin Compact Linear Collider -hiukkaskiihdyttimeen
Original languageEnglish
QualificationDoctor's degree
Awarding Institution
  • Aalto University
  • J. Ovaska, Seppo, Supervising Professor
  • Barnes, Michael J., Thesis Advisor
Print ISBNs978-952-60-6535-9
Electronic ISBNs978-952-60-6536-6
Publication statusPublished - 2015
MoE publication typeG4 Doctoral dissertation (monograph)


  • inductive adder
  • analogue modulation
  • droop compensation
  • ripple compensation


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