International Conference on Pulsed Power Applications Paper Number: F.01

Gelsenkirchen, March 27-29, 2001

P. Hoppé, R. Böhme, W. Frey, A. Weisenburger, H. Bluhm

Institut für Hochleistungsimpuls- und Mikrowellentechnik

Forschungszentrum Karlsruhe, Hermann-von-Helmholtz-Platz 1, P.O. box 3640

D-76021 Karlsruhe

Germany

DEMON-2 is a pulsed power device for the production of ceramic and metallic nanopowders by wire explosions. It consists mainly of 6 independent capacitor banks that can be used in parallel and charged to a maximum voltage of 35kV. The discharge of the banks is initiated by a triggered spark gap that feeds to a metallic wire placed in the reaction chamber. Depending on the energy coupled to the wire it is first heated up, then disintegrates into droplets or vapor, which finally precipitate into nanopowder in the chamber atmosphere. In this paper the influence of the discharge energy on the properties of the nanopowder will be presented. It was investigated by varying either the number of capacitor banks used in parallel or the charge voltage of the capacitor banks . Hence the measured discharge current coupled to the wire changed from 20 (1 bank) to 80kA (6 banks in parallel) and correspondingly the disintegration time of the wire occurred at earlier times. The amount of the electrical energy fed into the wire was estimated from measurements of the voltage drop across the wire and from circuit simulation calculations based on experiments with a short load. Depending on the number of driver banks used in parallel, the efficiency of the discharge changed from 25 to 95% for a 227mm long wire with 0.7mm diameter.