Physics & Astronomy ETDs

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The time development of a fully ionized, dense two-component plasma is investigated through the use of a one-dimensional particle simulation code. The plasma is initially composed of two distinct regions. One region is a uniform plasma in which electrons and ions are at the sane temperature and have no electric fields due to charge separ­ation. The other region contains a charge separation of electrons and ions resulting in an electric field. There also exists an electron current which produces a confining magnetic field. This is the sheath region between the neutral plasma and the confining magnetic field. The simulation occurs over a time period of 400ω-1pe in units of reciprocal electron plasma frequency. The mass ratio of ions to electrons is taken as 100. The computer simulation code is the P.I.C. (particle-in-cell) type con­sisting of one dimension in space and three dimensions in velocity Vx, Vy, and Vz. The system is collisionless.

The plasma physical model and the computer model are discussed. The results of the computer experiment indicate that an equilibrium situation is reached in which pressure balance is achieved between the plasma and the confining magnetic field. Electrostatic waves are identified and evidence exists for the Weibel-type instability. The stable magnetic sheath thickness agrees well with theoretical predictions. Agreement is obtained with theoretical predictions of energy exchange between the magnetic field and the electrons resulting in electron heating. Similarly good agree­ment is obtained with growth rate predictions of the magnetic field for Weibel-type instabilities.

The P.I.C. simulation of the plasma sheath structure shows that a method for initializing high beta plasma simulations has been found. Also the results show very good agreement with existing theories of micro­-instabilities of the Weibel-type in terms of sheath broadening and electron heating by means of energy exchange. Such phenomena are observed in real laboratory devices.

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Physics & Astronomy

First Committee Member (Chair)

Christopher Pratt Leavitt

Second Committee Member

Hargit Singh Ahluwalia

Third Committee Member

Daniel Nelson Payton

Fourth Committee Member

Willis Lynn Everett

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