arXiv subjects

Jimmy Schmoke

Publications and source records attributed to Jimmy Schmoke.

3 recordsLinked to original sources

arXiv2010

The effect of thermophoresis on the discharge parameters in complex plasma experiments

Thermophoresis is a tool often applied in complex plasma experiments. One of the usual stated benefits over other experimental tools is that changes induced by thermophoresis neither directly depend on, nor directly influence, the plasma parameters. From electronic data, plasma emission profiles in the sheath, and Langmuir probe data in the plasma bulk, we conclude that this assumption does not hold. An important effect on the levitation of dust particles in argon plasma is observed as well. The reason behind the changes in plasma parameters seems to be the change in neutral atom density accompanying the increased gas temperature while running at constant pressure.

physics.plasm-ph↗

arXiv2007

Vertical Dust Particle Chains-Mass and Charge Measurements

Dusty plasmas have generated a large amount of interest since the discovery of ordered structure (crystal) formation in experimentally generated complex plasmas in 1994. Dust particles within the plasma sheath generated in these complex plasmas can form vertical chains due to the streaming ion wakefield. For the simplest of these configurations (a two particle chain), the particle closest to the lower electrode will generally remain in the shadow of the particle farthest from the lower electrode. These results in the two particles feeling differing ion drag forces: the top particle is acted on by the ion drag force directed from the plasma to the lower electrode, while the bottom particle is acted upon by the resulting wakefield produced by the interaction of the upper particle with the ion drag force. This dynamic situation currently provides the best known experimental environment for examining the physics behind the ion drag force and its interaction with the plasma sheath. An experimental method for investigating the interaction between pair-particle chains based on modulating the bias on the lower electrode employing a DC bias modulation technique will be presented.

astro-ph↗

arXiv2004

Impact Studies Using a One Stage Light Gas Gun

The Center for Astrophysics,Space Physics, and Engineering Research (CASPER) has completed construction and calibration of a Light Gas Gun (LGG), which is used for low velocity impact studies. At geosynchronous orbit, space debris can impact commercial satellites at velocities of 500 m/s [1] reducing their useful lifetime. Additionally, there is an ever-increasing population of abandoned nonoperational satellites and related debris in these orbits [2]. Therefore, it is important to clearly understand the physics behind how such collisions can cause structural damage. This is most easily determined by measuring the damage incurred on representative material exposed to test collisions in the laboratory. Data collected in this manner will not only help illuminate the shock physics involved but can also aid in providing methods for designing advanced shielding for satellites.

physics.gen-ph↗