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Radio-frequency (RF) charged particle traps, such as the Paul trap or higher order RF multipole traps, may be used to trap quasi-neutral plasma. The presence of positive and negative plasma species mitigates the ejection of particles that occurs due to space charge repulsion. For symmetric species, such as a pair plasma, the trapped particle distribution is essentially equal for both species. For plasma with species of disparate charge-to-mass ratio, the RF parameters are chosen to directly trap the lighter species, leading to loss of the heavier species until sufficient net space charge develops to prevent further loss. Two-dimensional (2D) electrostatic particle-in-cell simulations are performed of cases with mass ratio m+/m− = 10, and also with ion–electron plasma. Multipole cases including order N = 2 (quadrupole) and higher order N = 8 (hexadecapole) are considered. The light ion-heavy ion N = 8 case exhibits particles losses less than 5% over 2500 RF periods, but the N = 8 ion–electron case exhibits a higher loss rate, likely due to non-adiabaticity of electron trajectories at the boundary, but still with low total electron loss current on the order of 10 μA. The N = 2 ion-electron case is adiabatic and stable, but is subject to a smaller trapping volume and greater initial perturbation of the bulk plasma by the trapping field.
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Centrifugal-electrostatic confinement fusion
A model for plasma confinement is developed and applied for describing an electrically confined thermonuclear plasma. The plasma confinement model includes both an analytical approach that excludes space charge effects and a classical trajectory Monte Carlo simulation that accounts for space charge. The plasma consists of reactant ions that form a non-neutral plasma without electrons. The plasma drifts around a negatively charged electrode. Conditions are predicted for confining a deuterium–tritium plasma using a 460 kV applied electric potential difference. The ion plasma would have a 20 keV temperature, a 1020 m−3 peak density, and a 110 keV average kinetic energy per ion (including drift and thermal portions at a certain point in the plasma). The fusion energy production rate is predicted to be 10 times larger than the energy loss rate, including contributions associated with both plasma loss to electrodes and secondary electron emission. However, an approach for enhancing the fusion power density may have to be employed to realize a practical use for centrifugal-electrostatic confinement fusion.
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- Award ID(s):
- 1803047
- PAR ID:
- 10538207
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- Physics of Plasmas
- Volume:
- 30
- Issue:
- 9
- ISSN:
- 1070-664X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1063/5.0161536
