8 research outputs found
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Rotational instabilities in the FRC: results of hybrid simulations
Simulations of rotational instabilities in the Field Reversed Configuration (FRC) using our quasineutral hybrid simulation code, AQUARIUS, have shown that m = 2 instabilities can occur for levels of ion rotation well below thresholds predicted by previous theory
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Compact toroidal plasmas: simulations and theory
Realistic FRC equilibria are calculated and their stability to the n = 1 tilting mode is studied. Excluding kinetic effects, configurations ranging from elliptical to racetrack are unstable. Particle simulations of FRCs show that particle loss on open field lines can cause sufficient plasma rotation to drive the n = 2 rotational instability. The allowed frequencies of the shear Alfven wave are calculated for use in heating of spheromaks. An expanded spheromak is introduced and its stability properties are studied. Transport calculations of CTs are described. A power balance model shows that many features of gun generated CT plasmas can be explained by the dominance of impurity radiation. It is shown how the Taylor relaxation theory, applied to gun generated CT plasmas, leads to the possibility of steady state current drive. Lastly, applications of accelerated CTs are considered
Modeling of Venus, Mars, and Titan
International audienceIncreased computer capacity has made it possible to model the global plasma and neutral dynamics near Venus, Mars and Saturn's moon Titan. The plasma interactions at Venus, Mars, and Titan are similar because each possess a substantial atmosphere but lacks a global internally generated magnetic field. In this article three self-consistent plasma models are described: the magnetohydrodynamic (MHD) model, the hybrid model and the fully kinetic plasma model. Chamberlain and Monte Carlo models of the Martian exosphere are also described. In particular, we describe the pros and cons of each model approach. Results from simulations are presented to demonstrate the ability of the models to capture the known plasma and neutral dynamics near the three objects