Plasma opening switch experiments on the Particle Beam Accelerator II

Summary form only given, as follows. The authors have developed and tested three different plasma-opening switch (POS) designs that use magnetic fields to control and confine the injected plasma. All three configurations couple current efficiently to a 5- Omega electron beam diode. In the first switch, a plasma generated by flashboard sources is injected into the 20- Omega magnetically insulated transmission line through six equally spaced 30 degrees -wide azimuthal segments. The magnetic field from conduction of current through the plasma spoke surrounds and helps to confine the plasma. The second switch uses a magnetically injected plasma (MIP) source. The opening current is determined by the intensity of a preimposed magnetic field at the anode that is used to inject the plasma and hold it in place. The switch opens after the magnetic pressure of the conduction current overcomes the pressure produced by the injecting magnetic field and the inertia of the plasma and pushes a gap open at the cathode. Once the switch opens, the machine current forces the plasma back into the anode. The rate of the current rise is faster (in excess of 2*10/sup 14/ A/s) into short-circuit loads than with the segmented POS. The third switch uses the same plasma source as the MIP POS and, to get more efficient coupling, adds a rapidly rising magnetic field at the cathode to increase the force pushing the plasma back into the anode. The current-toggled POS performs as well as the MIP POS when coupled to short-circuit and high-impedance loads. It also allows current to be coupled more efficiently when opening near the peak generator current than it would if only the pre-imposed magnetic field were used at the anode.<>