A 4 MA, 500 ns pulsed power generator CQ-4 for characterization of material behaviors under ramp wave loading

Abstract

A pulsed power generator CQ-4 was developed to characterize dynamic behaviors of materials under ramp wave loading, and to launch high velocity flyer plates for shock compression and hypervelocity impact experiments of materials and structures at Institute of Fluid Physics, China Academy of Engineering Physics. CQ-4 is composed of twenty capacitor and primary discharge switch modules with total capacitance of 32 μF and rated charging voltage of 100 kV, and the storage energy is transmitted by two top and bottom parallel aluminum plates insulated by twelve layers of polyester film with total thickness of 1.2 mm. Between capacitor bank and chamber, there are 72 peaking capacitors with total capacitance of 7.2 μF and rated voltage of 120 kV in parallel, which are connected with the capacitor bank in parallel. Before the load, there is a group of seven secondary self-breaking down switches connected with the total circuit in series. The peaking capacitors and secondary switches are used to shape the discharging current waveforms. For short-circuit, the peak current of discharging can be up to 3 ~ 4 MA and rise time varies from 470 ns to 600 ns when the charging voltages of the generator are from 75 kV to 85 kV. With CQ-4 generator, some quasi-isentropic compression experiments under ramp wave loadings are done to demonstrate the ability of CQ-4 generator. And some experiments of launching high velocity flyer plates are also done on CQ-4. The experimental results show that ramp wave loading pressure of several tens of GPa on copper and aluminum samples can be realized and the velocity of aluminum flyer plate with size of 10 mm × 6 mm × 0.35 mm can be accelerated to about 11 km/s and the velocity of aluminum flyer plate with size of 10 mm × 6 mm × 0.6 mm can be up to about 9 km/s, which show that CQ-4 is a good and versatile tool to realize ramp wave loading and shock compression for shock physics.

Elastic Behavior of Zirconia under Ramp Compression

“…Magnetically driven ramp compression experiments of <100> and <110> single crystal cubic zirconia were conducted on CQ-4 device to investigate the elastic behaviours and yield properties in different orientations. The principle of magnetically driven ramp compression can be found elsewhere [6]. The sketch map of target is shown in Fig.…”

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

“…In addition, controlling the rise time of the current pulse alters the loading strain rate, readily enabling experiments in a regime of 10 4 -10 6 s -1 . The shaped electrode panels ensure that the magnetic field is uniformly distributed across the loading surface, and that pressure propagates as a near planar wave through the thickness of panels [18,20]. The dependence of the pressure loading with time can be calculated by measuring the velocity of an electrode panel through an impedance matched window (PIN3 in Figure1) and applying a backwards integration method [21].…”

“…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. Using optimally shaped electrode panels, ramp wave pressures up to ~100 GPa can be produced in copper and higher impedance metals on CQ-4 [18,19]. Alternately using the magnetic pressure to launch aluminum flyer plates can produce velocities >15 kms-1 [20].…”

Dynamic behaviors of a Zr-based bulk metallic glass under ramp wave and shock wave loading

“…Ramp wave compression experiments were performed on CQ-4 device, 13 which is a compact pulsed power generator with a peak discharging current of 4 MA and a rising time of 500 ns. Ramp wave compression is also referred as quasi-isentropic compression, because the loading path is close to isentropic.…”