Collective Enhancement of Radial Transport in a Nonneutral Plasma

Eggleston, D. L.; O’Neil, T. M.; Malmberg, J. H.

doi:10.1103/physrevlett.53.982

Cited by 53 publications

(35 citation statements)

References 11 publications

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“…The first RW experiments on electron plasmas used excitation of m θ > 0 Trivelpiece-Gould (TG) modes (see Section V.A.2), to provide the required torque (Anderegg et al, 1998;Eggleston et al, 1984;Hollmann et al, 2000;Mitchell, 1993). Such waves can be excited easily; and upon damping, the wave angular momentum is transmitted to the bulk plasma particles (Hollmann et al, 2000;Kiwamoto et al, 2005;Soga et al, 2006).…”

Section: Coupling Via Trivelpiece-gould Modesmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

225

222

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In recent years, there has been a wealth of new science involving low-energy antimatter (i.e., positrons and antiprotons) at energies ranging from 10 2 to less than 10 −3 eV. Much of this progress has been driven by the development of new plasma-based techniques to accumulate, manipulate and deliver antiparticles for specific applications. This article focuses on the advances made in this area using positrons. However many of the resulting techniques are relevant to antiprotons as well. An overview is presented of relevant theory of single-component plasmas in electromagnetic traps. Methods are described to produce intense sources of positrons and to efficiently slow the typically energetic particles thus produced. Techniques are described to trap positrons efficiently and to cool and compress the resulting positron gases and plasmas. Finally, the procedures developed to deliver tailored pulses and beams (e.g., in intense, short bursts, or as quasi-monoenergetic continuous beams) for specific applications are reviewed. The status of development in specific application areas is also reviewed. One example is the formation of antihydrogen atoms for fundamental physics [e.g., tests of invariance under charge conjugation, parity inversion and time reversal (the CPT theorem), and studies of the interaction of gravity with antimatter]. Other applications discussed include atomic and materials physics studies and study of the electron-positron many-body system, including both classical electron-positron plasmas and the complementary quantum system in the form of Bose-condensed gases of positronium atoms. Areas of future promise are also discussed. The review concludes with a brief summary and a list of outstanding challenges.

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Section: Coupling Via Trivelpiece-gould Modesmentioning

confidence: 99%

Plasma and trap-based techniques for science with positrons

Danielson¹,

Dubin²,

Greaves³

et al. 2015

Rev. Mod. Phys.

225

222

View full text Add to dashboard Cite

show abstract

“…Once the base pressure is low enough to minimize electron-neutral transport, the confinement is limited by electric and magnetic fields that break the cylindrical symmetry of the trap and produce radial drifts. This asymmetryinduced transport has been studied experimentally by a number of people, [1][2][3][4][5][6][7][8][9] but detailed comparisons of the predictions of resonant particle transport theory 10 with experiment 7 show serious discrepancies. It seems clear that some important physics is missing from the theory.…”

Section: Introductionmentioning

confidence: 96%

Two sources of asymmetry-induced transport

Eggleston

2012

Physics of Plasmas

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A single-particle computer code with collisional effects is used to study asymmetry-induced radial transport of a non-neutral plasma in a coaxial Malmberg-Penning trap. Following the time variation of the mean change and mean square change in radial position allows for the calculation of the radial drift velocity v D and the diffusion coefficient D as defined by the radial flux equationFor asymmetries of the form / 1 ðrÞcosðkz þ xt À lhÞ and periodic boundary conditions, the transport coefficients obtained match those predicted by resonant particle transport theory where the transport is produced by particles with velocities near 6ðlx R À xÞ=k, with x R being the azimuthal rotation frequency. For asymmetries of the form / 1 ðrÞcosðkzÞcosðxt À lhÞ and low collision frequency, there is a second contribution to the transport produced by low velocity particles axially trapped in the asymmetry potential. These produce a stronger variation of D with x with a peak at x ¼ x R . The width of the peak Dx increases with center conductor bias and decreases with radius, while the height shows the opposite behavior. The transport due to axially trapped particles is typically comparable to or larger than that from resonant particles. This second contribution to the transport may explain the discrepancies between experiments and resonant particle theory. V C 2012 American Institute of Physics. [http://dx.

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“…Both spheroidal plasmas and long plasmas show strong confinement degradation when applied stationary perturbations coincide with a plasma mode. 5,7 In long electron plasmas, modest density and angular momentum increases were reported 8 when the applied perturbation excited a plasma mode, but strong heating was observed and background ionization made the technique impractical at low magnetic fields (Bр400 G͒.…”

Section: Introductionmentioning

confidence: 98%

“…Also, confinement degradation and heating have been observed when k z 0 modes have zero frequency in the lab frame, and thus are resonant with static field errors. 5,7 The first implementation of the rotating wall technique on an electron plasma 12 identified the k z 0 TrivelpieceGould ͑TG͒ plasma modes as the dominant mechanism coupling the rotating wall to the plasma. Here, we show that a k z 0 rotating wall perturbation couples to both electron plasmas and ion plasmas predominantly through excitation of these TG plasma modes.…”

Section: Introductionmentioning

confidence: 99%

Confinement and manipulation of non-neutral plasmas using rotating wall electric fields

Hollmann¹,

Anderegg²,

Driscoll³

2000

Physics of Plasmas

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A “rotating wall” perturbation technique enables confinement of up to 3×109 electrons or 109 ions in Penning–Malmberg traps for periods of weeks. These rotating wall electric fields transfer torque to the particles by exciting Trivelpiece–Gould plasma modes with kz≠0 and mθ=1 or 2. Modes that rotate faster than the plasma column provide a positive torque that counteracts the background drags, resulting in radial plasma compression or steady-state confinement in near-thermal equilibrium states. Conversely, modes that rotate slower than the plasma provide a negative torque, and enhanced plasma expansion is observed. The observed Trivelpiece–Gould mode frequencies are well predicted by linear, infinite-length, guiding-center theory.

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Collective Enhancement of Radial Transport in a Nonneutral Plasma

Cited by 53 publications

References 11 publications

Plasma and trap-based techniques for science with positrons

Plasma and trap-based techniques for science with positrons

Two sources of asymmetry-induced transport

Confinement and manipulation of non-neutral plasmas using rotating wall electric fields

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