Current Research
I work on the Large Plasma Device at UCLA's Basic Plasma Science Facility under Prof. Walter Gekelman. The LaPD is a world-class basic plasma research device, supporting a quiet 60cm x 16 meter strongly magnetized discharge plasma. My thesis is on the behavior of a dense, expanding laser-generated plasma within the LaPD background plasma.
Inside LaPD, a carbon (graphite) cylinder (2cm x 20cm) is suspended within the plasma. During the discharge, the inside face is illuminated by the pulse from a 10ns, 1.1J Nd:YAG laser, at an angle near normal to the background field. A dense (initial n ≈ 1015) plasma forms and propagates across the background field.
Beyond the large-scale dynamics, by far the most interesting aspect of the experiment is the complicated structure observed on the expanding plasma. Two-probe correlation measurements indicate the presence of large electrostatic structures on the plasma surface.
Also (as in previous laser experiments at LaPD), the electron currents generated by a pair of expanding laser plasmas create Alfven waves in the background plasma. The presence of two such current channels in this experiment leads to reconnection phenomena which is the subject of our recent publication in Physics of Plasmas.
Papers & Publications
Structure of a Dense Expanding Plasma
Seminar at NASA Goddard Space Flight Center
We observe the formation of a diamagnetic cavity, along with electrostatic structures at the edge of the expanding laser plasma.
Three-Dimensional Current Systems
Physics of Plasmas
Analysis of current systems generated by colliding laser-produced plasmas. Reconnection events are observed.
Two-Dimensional Micron-Step Probe Drive
Review of Scientific Instruments
Description of a two-dimensional probe platform to perform correlation measurements with sub-millimeter resolution.
Movies
Diamagnetic cavity (MPEG-4, 500k)
Z-component of magnetic field, showing diamagnetic effect of expanding plasma. Full-scale (red to blue) is a 95% reduction in B0 (600G).
Magnetic field 3cm downstream (Quicktime, 19MB)
Version of this experiment with two targets. The data show two electron current channels formed by the expanding plasma, and an "X-point" between them.
Magnetic field following plasma collision (AVI, 17MB)
Magnetic field data is collected in five 30cm x 30cm planes inside LaPD following the laser firing. This movie renders the 3-dimensional magnetic field vectors in those planes, along with isosurfaces of the axial current density calculated from B.
Fast photography of collision (AVI, 1.2MB)
Fast (3ns exposure) photo series composed from successive experiments with longer and longer camera trigger delays. Shows the bubble evolution with time. Of particular interest are the "fingers" (Rayleigh-Taylor?) which extend from the bubble surfaces, changing in both amplitude and wavelength over time.