High-Speed Macroparticle Destruction in a High-Current Pulse Discharge

The possibility of spacecraft's electrodynamic shielding (EDS) against high-speed orbital debris has been investigated both experimentally and theoretically. The laboratory EDS device is made as a flat two-electrode discharge unit. Its external electrode serves as the first shield in the incident particles' way while the internal electrode has a "brush" of thin conductors contacting it and directed towards the first electrode to meet particles with their free ends. Successful tests of the EDS were carried out at the speed of the coming aluminium particle ~2.0 km/s sized Oslash7.8times12 mm (mass ~1.7 g) while the voltage of about 5 kV was applied to the EDS electrodes from a capacitor battery of 4 mF (stored energy 50 kJ). Interelectrode distance ranged 60-75 mm and free ends of the "brush" conductors were separated from the external electrode by 1-2 mm, i.e. less distance than the size of the particle model. At the impact of the model particle EDS electrodes are short-circuited and the said capacitor is discharged with the following parameters of the discharge pulse: current up to ~250 kA, pulse duration ~70 mus. At these parameters an obstacle in the form of an aluminium plate 4 mm thick simulating a space object's hull remained intact while without this discharge it was perforated. Two theoretical approaches to the description of the discharge initiated by an incident particle with the eventual particle's destruction are proposed considering processes of its melting (evaporation) and deceleration. The comparison of theoretical discharge current integral with a real experimental value shows that the proposed notions describe the situation quite reasonably.