The operation of generalized Marx-type solid-state bipolar modulators is discussed and compared with simplified Marx-derived circuits, to evaluate their capability to deal with various load conditions. A comparative analysis on the number of switches per cell, fiber optic trigger count, losses, and switch hold-off voltages has been made. A circuit topology is obtained as a compromise in terms of operating performance, trigger simplicity, and switching losses. A five-stage laboratory prototype of this circuit has been assembled using 1200 V insulated gate bipolar transistors (IGBTs) and diodes, operating with 1000 V dc input voltage and 1 kHz frequency, giving 5 kV bipolar pulses, with 2.5 μs pulse width and 5 μs relaxation time into resistive, capacitive, and inductive loads.

Marx-Type Solid-State Bipolar Modulator Topologies: Performance Comparison

Low-temperature plasma with reactive species including the hydroxyl radical is found very effective for the degradation of many pharmaceuticals and macromolecular organic matter in wastewater. The most efficient way is to excite plasma directly in the wastewater using high-voltage sub-microsecond pulses which prevents the corona discharges developing into arc discharges. Recently, plasma generated with high-voltage pulses of only several hundred nanosecond durations has been found to be especially efficient. Therefore, an all solid-state sub-microsecond pulse generator prototype based on the Marx concept is constructed, with MOSFET power semiconductor devices. This pulse generator is able to generate rectangular pulses with adjustable durations in impedance-varying wastewater. The sub-microsecond signals are generated by field-programmable gate array, and simulations of the driving circuits are carried out to optimize the driving signals so as to trigger the switches synchronously in a few nanoseconds. First, experiments show that sub-microsecond pulses with amplitudes over 7 kV and a minimum pulse duration of about 100 ns can be generated. Both rise time and fall time are about 22 ns. Pulse frequency up to 30 kHz is achieved. Besides, most of these parameters can be adjusted. The pulse generator itself is compact and portable.

All Solid-State Rectangular Sub-Microsecond Pulse Generator for Water Treatment Application

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.; Vaitoskirjassa esitetaan suunnitteluaskeleet ja kaksi prototyyppilaitetta erittain suuren tarkkuuden pulssiteholahteen toteuttamiseen. Tutkimus on osa Compact Linear Collider (CLIC) -kiihdyttimen toteutettavuustutkimusta. CLIC-hiukkaskiihdyttimessa kaytetaan esivaimennuspiireja (Pre-Damping Ring) ja vaimennuspiireja (Damping Ring), joilla saavutetaan synkrotronisateilya hyodyntaen erittain alhainen hiukkassuihkun emittanssi. Vaimennuspiirien ohjausmagneetteja syottavien pulssiteholahteiden taytyy tuottaa aarimmaisen tasalatvaisia korkeajannitteisia pulsseja. Teholahteen vaatimukset vaimennuspiirin 2 GHz:n perustaajuudella toimivalle versiolle ovat seuraavat: 160 ns:n pituinen tasalatvainen pulssi 12.5 kV:n jannitteella ja 250 A:n virralla, jonka yhdistetty amplitudin vaihtelu ja…

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

This paper presents the design for a novel all solid-state sub-microsecond pulse generator for dielectric barrier discharges (DBDs). This generator consists of a MARX generator, Blumlein transmission lines (BTLs) and one magnetic switch (MS). As a power supply, the all solid-state MARX generator is capable of outputting nanosecond-pulses with a voltage peak of up to 20 KV. The key elements are BTLs which are charged by the MARX generator. Due to the unmatched impedance of DBD load, energy stored in BTLs begins to oscillate through DBD load after the MS turns on. The violent oscillation lasts until all the energy is consumed. During the violent oscillation, over ten discharges are excited in 5 μs under a single-shot condition. Thus, extremely intense plasma can be produced due to the accumulation effect. The alternating-current decaying voltage over the MS has a demagnetization effect, and DC reset circuit can therefore be spared. Experiments with matched resistor load were also carried out, and rectangular pulses with voltage up to 20 kV and duration of 220 ns were obtained. The ratio of the energy consumed by the resistor from the energy stored in the BTLs is 84.9%. The DBD images under a single shot and 100 Hz are presented.

A Novel All Solid-State Sub-Microsecond Pulse Generator for Dielectric Barrier Discharges

Sub-nanosecond bipolar high voltage pulses are a very important tool for food processing, medical treatment, waste water and exhaust gas processing. A Hybrid Modulator for sub-microsecond bipolar pulse generation, comprising an unipolar solidstate Marx generator connected to a load through a stack Blumlein system that produces bipolar pulses and further multiplies the pulse voltage amplitude, is presented. Experimental results from an assembled prototype show the generation of 1000 V amplitude bipolar pulses with 100 ns of pulse width and 1 kHz repetition rate.

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Solid state marx modulator with blumlein stack for bipolar pulse generation

A newly developed bipolar high voltage adder is proposed for generating fast narrow pulses The new circuit topology enables the use of typical half-bridge semiconductor structures on the basis of conventional unipolar all-solid-state pulse adder Magnetic ring transformers were employed for isolating the charge loop from the high-voltage pulse discharge loop, which simplified the isolation arrangement Certain measures were implemented to resolve the EMI caused by the pulse adder arrangement A laboratory prototype was assembled with 8 stages and each stage was made of 800 V MOSFETs The modulator operating at 21 kHz repetition rate gives 2 kV bipolar pulses, with 200 ns positive/negative pulse widths, 37 ns rise time, 50 ns fall time, and 40 ns relaxation time into a 50 Ω resistive load The adopted design is an all-solid-state approach with a simple control method, long maintenance-free lifetime, and high reliability

All-solid-state pulse adder with bipolar high voltage fast narrow pulses output

A newly developed bipolar high-voltage modulator topology, based on fully integrated solid-state Marx generator circuit, is proposed for generating fast narrow pulses. The new circuit topology combines the advantages of conventional unipolar all-solid-state Marx modulator concepts, which takes advantage of the intensive use of power semiconductor switches, enables the use of typical half-bridge semiconductor structures. Magnetic ring transformers are used for isolating of charging circuit from high voltage pulse output, which simplified the isolation arrangement. The main factors which affect the rising and falling edge of the output pulses are discussed on the basis of simulations and experimental results. A laboratory prototype is composed of 8 stages and each stage is made of 800 V MOSFETs. The modulator operating at 2 kHz repetition rate gives 2 kV bipolar pulses, with 200 ns pulse width, 53 ns rise time, 70ns fall time and 500 ns relaxation time into a 50 Ω resistive load.

Lan Gao

Papers

All-solid-state pulse adder with bipolar high voltage fast narrow pulses output

All solid-state Marx modulator with bipolar high-voltage fast narrow pulses output