A magnetic acceleration plasma facility for plasma shock peening

Abstract

Set-up, function and application potential of pulsed magnetoplasmadynamic self-field accelerators are described. The focus is on the facility MAX (Magnetoplasmadynamic Accelerator-eXperiment). Here, a high power coaxial accelerator is investigated regarding space propulsion and processes aiming for metal treatment as potential applications. A certain amount of gas is accelerated via magnetic fields while the overall kinetic energy of the plasma has to be maximized. During plasma generation numerous parasitic effects are associated with the discharge of the device. Hence, the characterization of the facility in terms of power balance, functional behaviour and kinetic energy of the plasma is mandatory. The kinetic energy is of importance for both space propulsion and the mentioned plasma material treatment processes. Electrodynamic properties enabling the simulation with a snowplow model have been determined experimentally. The model provides a relation between the plasma movement and the electrodynamic properties. Results of the model are current and voltage histories but also statements on the kinetic energy of the plasma. Based on this calorimeters were designed, manufactured and integrated using adequate measurement technology, e.g. fast thermocouples and an infrared camera allowing for the determination of the temporal and spatial temperature histories on the calorimeters. A thermal analysis model was developed and applied to the calorimeter and compared with the measurements. Hence, the thermal energy could be determined which consequently led to an efficiency of 12% for a load voltage of 12 kV and an ambient pressure of 10 −5 mbar.