Investigation of Magnetic Field Curvature on Plasma-Induced Magnetic Flux Compression in a Stator Coil*

     In this experiment, the effect of field curvature on magnetic flux compression in a stator coil was investigated. A laser-produced plasma (LPP) was created within an externally applied magnetic field. The magnetic field was created using various permanent magnets introducing different types of field curvature. The plasma is created by focusing a pulsed Nd: YAG laser with a wavelength of 532 nm onto a graphite target placed within the externally applied magnetic field. The stator coil used in the experiment contains 40 turns of wire and is placed in front of the graphite target with the plasma expanding inside of it. To test the effect of field curvature, three different magnetic field configurations are tested. These include a straight field geometry created by bar magnets and concave-outward and inward directed fields created by cylindrical magnets. The experiment was carried out in a vacuum chamber set to a pressure of 10^-5 Torr and a laser energy of 100 mJ was used to create the plasma. ICCD imaging data has been collected showing plasma expansion into the magnetic field and voltage measurements from the stator coil show induced currents created in stator coils. Initial data indicate slightly more induced current (and thus more field compression) in the concave-outward field geometry compared to the straight field geometry produced by the bar magnets.