dorsal/arxiv
View SchemaBreakdown of adiabatic invariance in spherical tokamaks
| Authors | Johan Carlsson |
|---|---|
| Categories | |
| ArXiv ID | physics/0105105 |
| URL | https://arxiv.org/abs/physics/0105105 |
| DOI | 10.1063/1.1412008 |
| Journal | Physics of Plasmas 8, (2001) 4725 |
Abstract
Thermal ions in spherical tokamaks have two adiabatic invariants: the magnetic moment and the longitudinal invariant. For hot ions, variations in magnetic-field strength over a gyro period can become sufficiently large to cause breakdown of the adiabatic invariance. The magnetic moment is more sensitive to perturbations than the longitudinal invariant and there exists an intermediate regime, super-adiabaticity, where the longitudinal invariant remains adiabatic, but the magnetic moment does not. The motion of super-adiabatic ions remains integrable and confinement is thus preserved. However, above a threshold energy, the longitudinal invariant becomes non-adiabatic too, and confinement is lost as the motion becomes chaotic. We predict beam ions in present-day spherical tokamaks to be super-adiabatic but fusion alphas in proposed burning-plasma spherical tokamaks to be non-adiabatic.
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"abstract": "Thermal ions in spherical tokamaks have two adiabatic invariants: the\nmagnetic moment and the longitudinal invariant. For hot ions, variations in\nmagnetic-field strength over a gyro period can become sufficiently large to\ncause breakdown of the adiabatic invariance. The magnetic moment is more\nsensitive to perturbations than the longitudinal invariant and there exists an\nintermediate regime, super-adiabaticity, where the longitudinal invariant\nremains adiabatic, but the magnetic moment does not. The motion of\nsuper-adiabatic ions remains integrable and confinement is thus preserved.\nHowever, above a threshold energy, the longitudinal invariant becomes\nnon-adiabatic too, and confinement is lost as the motion becomes chaotic. We\npredict beam ions in present-day spherical tokamaks to be super-adiabatic but\nfusion alphas in proposed burning-plasma spherical tokamaks to be\nnon-adiabatic.",
"arxiv_id": "physics/0105105",
"authors": [
"Johan Carlsson"
],
"categories": [
"physics.plasm-ph"
],
"doi": "10.1063/1.1412008",
"journal_ref": "Physics of Plasmas 8, (2001) 4725",
"title": "Breakdown of adiabatic invariance in spherical tokamaks",
"url": "https://arxiv.org/abs/physics/0105105"
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