A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments

Abstract

A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak current of new generators can be increased to 5-6 MA and about 100 GPa ramp stress can be produced on the metallic samples for high pressure physics, and a conceptual design of CQ-5-MMAF was given.

Characterizations of dynamic material properties on compact pulsed power generator CQ-4

“…Recent many experiments demonstrate that the technique of magnetically driven ramp wave (quasi-isentropic) compression and launching high velocity flyer plates based on pulsed high current generators is a very precise experimental method to do researches on the dynamic material properties under ramp wave and shock compression [12][13][14][15], which can realize loading pressures from tens of GPa to several TPa and strain rates from 10 4 /s to 10 7 /s. Since 2003, the compact CQ series pulsed power generators for ramp wave and shock experiments were developed to cover loading pressures from tens of GPa to several hundred GPa at Institute of Fluid Physics(IFP), China Academy of Engineering Physics(CAEP) [16,17]. CQ-4 is one of them, which can deliver pulsed currents with peak value of 3~4 MA and rise time of 470 ns~600 ns to short circuit loads.…”

A compact platform for the investigation of material dynamics in quasi-isentropic compression to ~ 19 GPa

“…There are technical and economic difficulties in developing such large facilities. Meanwhile, some laboratories have developed relatively compact pulsed power devices, such as Veloce 29 , Phelix 30 , GEPI 31 , CEPAGE 32 , and the CQ series 25,33 . These facilities usually output current of 1-10 MA and thus have a much lower loading ability.…”