Factors affecting synthesis of single wall carbon nanotubes in arc discharge

In this paper a model of single wall carbon nanotube (SWNT) interactions with thermal plasma is developed. Several effects such as momentum, charge and energy transfer between the SWNT and plasma are considered. It is shown that the SWNT charge and potential with respect to the plasma, as well as SWNT aspect ratio, depend on plasma density and electric field in the interelectrode gap. For instance, the SWNT charge changes from negative to positive value with electron density decrease. This model suggests several ways to improve the controllability of SWNT synthesis in arc discharge, such as an increase in plasma density and the application of an electric field. It is predicted that higher plasma density in the SWNT formation region and electric field lead to the formation of SWNT with a very high aspect ratio.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58139/2/d7_8_s18.pd

GW-Sat: GW\u27s First Satellite with Propulsive 3-Axis-Stabilization

The George Washington University’s proposed satellite mission, GW-Sat, was one of the 34 missions selected by NASA as part of the CubeSat Launch Initiative program. The CubeSat will be built entirely by students from different departments and schools at the university. GW-Sat is a 3 U CubeSat and its primary mission is to validate its propulsion system based on in-house built Micro-Cathode Arc Thrusters. The thrusters will be used to provide the spacecraft with 3-axis stabilization and the ability to perform station-keeping maneuvers, and therefore, increase the mission’s lifetime. In addition to this, the CubeSat will be used to perform secondary science missions, which include relaying information from a remote ground station using the store-forward architecture and the effect of the thruster’s plasma discharges on radio communications

Plasma Processes and Polymers Special Issue on: Plasma and Cancer

During the last two decades, research efforts on the application of low temperature plasmas in biology and medicine have positioned nonequilibrium lowtemperature plasmas as a technology that has the potential of revolutionizing healthcare.[1,2] Low temperature plasmas can be applied in direct contact with living tissues to inactivate bacteria,[3] to disinfect wounds and accelerate wound healing,[4] and to induce damage in some cancer cells.[5–11

On the magnetic mirror effect in Hall thrusters

The magnetic mirror effect is studied in the channel of a Hall thruster. It is shown that gradients in magnetic field affect the presheath structure and electric potential distribution. The length of the radial presheath region decreases in the presence of a magnetic field gradient. The two-dimensional potential shape can be affected by proper choice of the magnetic mirror ratio. In particular, it is possible to obtain a concave shape of the potential profile in the channel even in the case of a primarily radial magnetic field. This, in turn, can be used to efficiently control the ion dynamics in the acceleration region.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87826/2/121501_1.pd

Device and plume model of an electrothermal pulsed plasma thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76705/1/AIAA-2000-3430-801.pd

Nonequilibrium thermal boundary layer in a capillary discharge with an ablative wall

A thermal nonequilibrium region near wall in a capillary discharge is considered. The proposed model suggests that nonequilibrium thermal boundary layer thickness strongly depends on the capillary wall ablation rate. It is shown that the applicability of the thermal equilibrium condition, widely employed in capillary models, is limited to a case with a large ablation rate.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87756/2/114503_1.pd

Ablation study in the capillary discharge of an electrothermal gun

In this paper, we study the ablation phenomena associated with the operation of a capillary discharge for an electrothermal gun. Electrothermal-chemical (ETC) guns are used for enhancement of ignition and combustion of an energetic propellant. One of the major components of the ETC system is a plasma source based on a capillary discharge. In this paper, a model of the capillary discharge is developed. In this model, primary attention is paid to the ablation phenomenon. Different characteristic subregions near the ablated surface, namely, a space-charge sheath, a Knudsen layer, and a hydrodynamic layer, are considered. In this formulation, the ablation rate is determined by the parameters at the edge of the Knudsen layer. The kinetic approach is used to determine the parameters at the interface between the kinetic Knudsen layer and the hydrodynamic layer. Coupling the solution of the nonequilibrium Knudsen layer with the hydrodynamic layer provides a self-consistent solution for the ablation rate. According to the model predictions, the peak electron temperature is about 1.4 eV, the polyethylene surface temperature is about 700 K, and the pressure is about 10 MPa. It is found that the ablation rate increases with the capillary length. The ablated mass and the predicted total pressure agree with previous experimental observations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87444/2/053301_1.pd

Electromagnetic effects in the near field plume exhaust of a pulsed plasma thruster

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77043/1/AIAA-2001-3638-544.pd