[IEEE The 31st IEEE International Conference on Plasma Science, 2004. ICOPS 2004. IEEE Conference...
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1P16 1P17 Plasma Toroid Formation by Polyphase Microwave Rotation Charge Conserving Current Weights for PIC: Application to Cylindrical Coordinates G. B. Kirby Meacham Meacham Company Andrew D. Greenwood and Keith L. Cartwright Air Force Research Laboratoly, Directed EnergV Directorate Reported microwave-plasma interactions that simulate ball lightning may point the way to useful applications including improved elec- trode-less arc lamps and sustained plasma confinement for fusion reactors. Natural lightning balls are seemingly self-organized dynam- ic shuctures associated with electrical storms and lightning strikes. They emit light and persist for a number of seconds, and move in ways that suggest that they are influenced by electromagnetic forces. While there is no firmly established explanation for ball lightning, one theo- ry is that the balls are toroidal plasma bodies formed by electrical dis- charge transients and held together by internal current loops and mag- netic fields. Toroidal plasma bodies formed by transient processes have been investigated to confine plasma for nuclear fusion'. Since no simple way has been found to sustain the direct current internal cur- rent loop required for plasma confinement and heating, they are formed and then decay. Electrode-less arc lamps use oscillating elec- tric fields, magnetic fields, or a combination of the two to induce an alternating current plasma arc in a transparent envelope without elec- trodes'. Direct current electrode-less arc lamps are not possible using this technique. The reported microwave-plasma experiments'.' form and sustain glowing balls, resembling ball lightning, using microwave energy through a mechanism that is not well understood. I hypothe- size that the observed effect occurs at points in a microwave enclosure where orthogonal standing waves with 90" phase difference form a rotating electrical field vector that induces plasma rotation. Further, I hypothesize that this rotating conductive plasma generates a voltage loop through BxV dynamo interaction with an ambient steady mag- netic field to form standing direct current loops that heat plasma and confine it in a toroid through the IxB pinch effect. This is a testable hypothesis, which, if confirmed, provides a new approach for lamp and fusion confinement systems. It is even possible that it may help understand naturally occurring ball lightning. 'K. Miyamoto: Plasma Physics for Nuclear Fusion Revised Edition: pp. 529-532, The MIT Press, Cambridge (1987). 'Kirkpatrick, et al., US Patent 6,424,099, (2002). 'Y. H. Ohtsuki and H. Ofuruton, Nature 350, 139-141 (1991). 'Branderburg, et al., US Patent 6,441,552 (2002). Particle in cell (PIC) codes successfully model devices containing charged particles in electromagnetic fields. The motion of the parti- cles generates currents that must be weighted to the cell edges in a charge conserving manner. The Villasenor-Buneman scheme accom- plishes the current weighting for cnhic cells. However, the use of cubic cells results in problematic staircase approximations to surfaces that are not aligned to one of the gnd axes. PIC codes with alternate cell shapes are proposed to avoid the staircase approximation; thus, current weighting schemes are needed for arbitrary cell shapes. The Whitney I-form basis functions used with the finite element method are used to derive charge conserving current weights on the alternate cell shapes. The presentation will describe the derivation of c w e n t weights and prove that the result is charge conserving. The derivation is applied to cubes, prisms, and tetrahedrons in 3-D, and to rectangles and triangles in 2-D. When applied to cubes, the derivation recovers the well known Villasenor-Buneman current weights. The derivation is also used to find charge conserving current weights for PIC codes in cylindrical coordinates. Cells away from the cylin- drical axis are mapped into cubes, and current weights are then found. Cells next to the cylindncal axis arc mapped into triangular prisms, and current weights are found. The cylindrical coordinate current weights are shown to be charge conserving. The cment weights in cylindrical coordinates are tested by implementation in the Improved Concurrent Electromagnetic Particle in Cell (ICEPIC) code. 134
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1P16 1P17
Plasma Toroid Formation by Polyphase Microwave Rotation
Charge Conserving Current Weights for PIC: Application to Cylindrical Coordinates
G. B. Kirby Meacham
Meacham Company
Andrew D. Greenwood and Keith L. Cartwright
Air Force Research Laboratoly, Directed EnergV Directorate
Reported microwave-plasma interactions that simulate ball lightning may point the way to useful applications including improved elec- trode-less arc lamps and sustained plasma confinement for fusion reactors. Natural lightning balls are seemingly self-organized dynam- ic shuctures associated with electrical storms and lightning strikes. They emit light and persist for a number of seconds, and move in ways that suggest that they are influenced by electromagnetic forces. While there i s no firmly established explanation for ball lightning, one theo- ry is that the balls are toroidal plasma bodies formed by electrical dis- charge transients and held together by internal current loops and mag- netic fields. Toroidal plasma bodies formed by transient processes have been investigated to confine plasma for nuclear fusion'. Since no simple way has been found to sustain the direct current internal cur- rent loop required for plasma confinement and heating, they are formed and then decay. Electrode-less arc lamps use oscillating elec- tric fields, magnetic fields, or a combination of the two to induce an alternating current plasma arc in a transparent envelope without elec- trodes'. Direct current electrode-less arc lamps are not possible using this technique. The reported microwave-plasma experiments'.' form and sustain glowing balls, resembling ball lightning, using microwave energy through a mechanism that is not well understood. I hypothe- size that the observed effect occurs at points in a microwave enclosure where orthogonal standing waves with 90" phase difference form a rotating electrical field vector that induces plasma rotation. Further, I hypothesize that this rotating conductive plasma generates a voltage loop through BxV dynamo interaction with an ambient steady mag- netic field to form standing direct current loops that heat plasma and confine it in a toroid through the IxB pinch effect. This is a testable hypothesis, which, if confirmed, provides a new approach for lamp and fusion confinement systems. It is even possible that it may help understand naturally occurring ball lightning.
'K. Miyamoto: Plasma Physics for Nuclear Fusion Revised Edition: pp. 529-532, The MIT Press, Cambridge (1987). 'Kirkpatrick, et al., US Patent 6,424,099, (2002). 'Y. H. Ohtsuki and H. Ofuruton, Nature 350, 139-141 (1991). 'Branderburg, et al., US Patent 6,441,552 (2002).
Particle in cell (PIC) codes successfully model devices containing charged particles in electromagnetic fields. The motion of the parti- cles generates currents that must be weighted to the cell edges in a charge conserving manner. The Villasenor-Buneman scheme accom- plishes the current weighting for cnhic cells. However, the use of cubic cells results in problematic staircase approximations to surfaces that are not aligned to one of the gnd axes. PIC codes with alternate cell shapes are proposed to avoid the staircase approximation; thus, current weighting schemes are needed for arbitrary cell shapes. The Whitney I-form basis functions used with the finite element method are used to derive charge conserving current weights on the alternate cell shapes. The presentation will describe the derivation of cwen t weights and prove that the result is charge conserving. The derivation is applied to cubes, prisms, and tetrahedrons in 3-D, and to rectangles and triangles in 2-D. When applied to cubes, the derivation recovers the well known Villasenor-Buneman current weights.
The derivation is also used to find charge conserving current weights for PIC codes in cylindrical coordinates. Cells away from the cylin- drical axis are mapped into cubes, and current weights are then found. Cells next to the cylindncal axis arc mapped into triangular prisms, and current weights are found. The cylindrical coordinate current weights are shown to be charge conserving. The cment weights in cylindrical coordinates are tested by implementation in the Improved Concurrent Electromagnetic Particle in Cell (ICEPIC) code.
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