This paper presents experimental results on the effects of insulating coatings and current prepulse on tungsten planar wire array Z-pinches on ∼100 ns main current facility. Optical framing images indicated that without a current prepulse the wire ablation process was asymmetrical and the implosion was zippered. The x-ray peak power was ∼320 GW. By using insulating coatings on the wire surface the asymmetry remained, and the processes of ablation and implosion were delayed by ∼30 ns. The x-ray burst was narrow and decreased to ∼200 GW. When current prepulses were used on both standard and insulated wire arrays, implosion symmetry was improved and the x-ray burst was improved (to ∼520 GW peak power). In addition, there was a strong emitting precursor column for insulated loads with the current prepulse.
Planar wire array Z pinches were carried out on the QiangGuang-I facility (1.3 MA, 100 ns). The effect of prepulse current and insulating coatings on the Z pinch behavior is investigated. Commonly there is a multichannel gas switch filled with 0.5 Mpa dry air between the transmission line and the MITL to cut off the prepulse current. By varying gas pressure filled in the switch, the parameters of the prepulse current can be controlled. With a 0.2 Mpa pressure the prepulse amplitude and duration are 70 kA and 200 ns respectively. The total width and length of the single planar wire array loads are 15 mm and 2 cm respectively. The standard loads consist of ten tungsten wires with diameter of 15 m. And for insulating loads there are 5 m Polyimide coatings over the wires. Both two types of planar wire array loads were studied on QiangGuang-I facility with and without the prepulse current.
This paper presents experimental results on the effects of insulating coatings on tungsten planar wire array Z-pinches on an 80 kA, 100 ns current facility. Expansion velocity is obviously increased from ∼0.25 km/s to ∼3.5 km/s by using the insulating coatings. It can be inferred that the wire cores are in gaseous state with this fast expansion velocity. An optical framing camera and laser probing images show that the standard wire arrays have typical ablation process which is similar to their behaviors on mega-ampere facilities. The ablation process and precursor plasma are suppressed for dielectric tungsten wires. The wire array implosion might be improved if these phenomena can be reproduced on Mega-ampere facilities.
In the present study, CR-39 detectors with thickness of 1.0mm are irradiated respectively by C3+(10MeV, 20MeV, 20MeV), O3+(10MeV, 20MeV, 30MeV) particles and protons (5MeV) with ion fluences ranging from 1.0×107cm−2 to 5.0×109cm−2. The etching time conditions of the latent tracks for the different irradiation particles with different fluences described above are experimental studied. The curves for track density distributions with irradiation fluences of different energy particles are simulated. The suggested irradiation fluences ranges for the three types of particles detected with CR-39 detector are offered according to the measurement results.
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