Impedance-matched Marx generators

Abstract

We have conceived a new class of prime-power sources for pulsed-power accelerators: impedancematched Marx generators (IMGs). The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-poweroutput time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

A Primer on Pulsed Power and Linear Transformer Drivers for High Energy Density Physics Applications

“…An LTD spinoff technology called an Impedance-matched Marx Generator (IMG) [118]. (a) A full coaxial 10-stage IMG [118]. (b) A 10-stage, single-brick-per-stage IMG [118].…”

“…(a) A full coaxial 10-stage IMG [118]. (b) A 10-stage, single-brick-per-stage IMG [118]. IMGs save cost and weight by removing the parasitic current path at each stage and therefore removing the need for heavy, expensive ferromagnetic cores (compare with Figs.…”

“…Recently, the development of an LTD spinoff technology called an Impedance-matched Marx Generator (IMG) has further blurred the lines between an LTD module and a Marx generator [118] (see Fig. 25).…”

Design of a 5-MA 100-ns linear-transformer-driver accelerator for wire array Z-pinch experiments

“…This high efficiency provides a strong motivation for the pursuit of relevant technologies, such as the lineartransformer-driver (LTD), which was initiated by the High Current Electron Institute (HCEI) in Russia [8][9][10][11][12][13][14]. Considerable work [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] has been conducted worldwide over the past 15 years in development of LTD components and systems.…”

“…An experimental investigation using five 1-MA LTD cavities assembled in series into a voltage adder was conducted [12,19]. Meanwhile, waterline-based LTD drivers were proposed for petawatt-class Z-pinch accelerators [20][21][22], utilizing monolithic triplate radial-transmission-line impedance transformers to converge the output of LTD modules toward the vacuum section. However, it was assumed to use a six-level 6-mdiameter 24-MV vacuum insulator stack [20], which is a great challenge compared to the present 3.2-m-diameter 3.1-MV stack currently used in the Z accelerator.…”