Kent A. Chambers PhD - SACS - Hardin-Simmons University

Summer 1997
and Summer
1998
June 1994
to August 1996
KENNETH F. STEPHENS II, PHD
the presheath, a system of nonlinear equations is obtained that describes the
electric potential within the sheath. The kinetic properties of the constituent
particles are thus determined.
Developed an approach to approximate the space-charge limited current of
relativistic electron beams in finite-length coaxial drift tubes. Defined as the
maximum steady-state current that can be transmitted through a certain
volume, the limiting current is difficult to determine for a general geometry due
to the inherent non-linearity of Poisson’s equation. Applying Green’s second
theorem to the space-charge limited Poisson equation over the beam’s volume,
a Sturm-Liouville eigenvalue equation can be introduced such that its boundary
conditions ensure Green’s identity. The limiting current is then approximated in
terms of the eigenvalue.
Along with the above research, a two-dimensional particle in cell (PIC) code
was developed to provide numerical comparison with the sheath and limiting
current theories. It was also used to investigate the ability of virtual cathodes to
simulate nested-well plasma traps. Other research interests included quantum
phase space propagators, transmission properties of one-dimensional quantum
structures and the electromagnetic characteristics of helical conductors.
Researcher/Programmer, Air Force Research Laboratory,
Kirtland Air Force Base, Albuquerque, New Mexico.
Modified and tested the Air Force’s 2-½ dimensional radiative magnetohydrodynamic
code, MACH2, and used it to model several devices of interest to
the scientific community: explosively formed fuses and magnetized target
fusion.
An explosively formed fuse is a fast opening switch capable of transferring
mega-joules of electrical energy within a few microseconds. The switch was
simulated by allowing an electrical current to flow through a thin foil,
surrounding a high-explosive. Detonating the explosive causes the foil to
lengthen and thin, thereby increasing its resistance. Using a preliminary current
of 1 kilo-ampere, details necessary for thoroughly modeling the device were
determined.
Magnetized target fusion is an approach to fusion ignition that is intermediate
to inertially-confined and magnetically-confined fusion schemes. Although a
magnetic field is used to inhibit thermal conduction from the plasma to the
confining liner, plasma-wall mixing still poses a problem. When this mixing
occurs, increased impurities in the plasma reduce the plasma temperature and
prevent the plasma from reaching ignition conditions. This mixing, due to the
Rayleigh-Taylor instability, was investigated by considering an imploding
cylindrical liner.
Teaching Assistant, University of North Texas, Denton,
Texas.
Taught the closed lab for calculus-based physics. Instructed students in the
open physics lab for all levels of introductory physics courses. Facilitated the
senior-level experimental physics lab and instructed the musical acoustics lab
for music majors.
2