Opening Switch Research on a Dense Plasma Focus.
Final rept. 30 Sep 84-29 Sep 86,
ILLINOIS UNIV AT URBANA NUCLEAR ENGINEERING LAB
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Several experiments were performed to enhance power coupling to the load by placing the load electrode opposite the muzzle end of the Dense Plasma Focus plasma gun. The impaler concept, whereby the current sheath is run into a knife edge insulator, was tested in two configurations. However, the power coupled to the load was always less than one tenth that of the experiments where the load was coupled to the breach of the gun. Other load coupling schemes where the load electrode was brought near the outside of the central electrode prevented pinches voltage surges when placed too close and the power coupled to the load was reduced when the load electrodes were moved away. The results of these latter experiments were in no case even as good as those of the impaler concept. Measurements of the dynamics of the current sheath in various stages were performed and compared with theory especially in regard to the circuit parameter dLdt. Generally the velocity of the current sheath falls below theoretical expectations suggesting the presence of electrode drag, a phenomenon not present in the model. During the radial collapse phase when the dLdt is the most important the model and the experimental estimates of dLdt are in substantial agreement before pinch time but disagree afterward due to two dimensional effects not present in the theory.
- Plasma Physics and Magnetohydrodynamics