Two Regimes of Asymmetry-Induced Transport in Non-neutral Plasmas

Kriesel, Jason M.; Driscoll, C. F.

doi:10.1103/physrevlett.85.2510

Cited by 46 publications

(46 citation statements)

References 27 publications

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“…It was found that tile mobility time T,, depends nearly linearly on the line density, as shown in Fig. 6 (recently, it was found that T,, for "rigid" columns depend linearly on density, but only same-size columns were compared [6] in that study).…”

Section: Asymmetry-dominated Transportmentioning

confidence: 92%

Decay of the Diocotron Rotation and Transport in a New Low-Density Asymmetry-Dominated Regime

2002

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Abstract. The decay of the diocotron rotation was studied in a new regime in which trap asymmetries dominate. The decay does not conserve angular momentum, and is strongest for small, low-density columns. For such columns decay of the diocotron mode within few diocotron periods was observed, orders of magnitude faster than the rotational pumping prediction. However, transition to decay dominated by rotational pumping was observed for larger and denser columns. The new regime is characterized by "magnetron-like" rotation in the trap, dominated by the end confinement fields. The asymmetry-dominated transport was also studied, and found to depend linearly on the line density (and not the density) over nearly 4 orders of magnitude.

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Section: Asymmetry-dominated Transportmentioning

confidence: 92%

Decay of the Diocotron Rotation and Transport in a New Low-Density Asymmetry-Dominated Regime

2002

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“…This may indicate a transition to bananaregime scaling, but the data is not sufficient to support this conclusion. Note that there is no dramatic dependence of m on radius, so if we were to calculate the expansion rate Av as in reference [8] the low amplitude scaling would still be 0. Further exploration of our parameter space has found some cases showing scaling closer to 0' and some of these cases are shown in Figure 4.…”

Section: Resultsmentioning

confidence: 99%

“…The presence of such asymmetries would produce a radial component to the E x B drift that would lead to particle loss to the walls of the trap. This suggestion led to a number of experiments [2][3][4][5][6][7][8] employing applied asymmetries in order to study the transport in a controlled manner. Most of the experiments have used electric asymmetries since these are easily applied and manipulated using the sectored wall portions of the confinement region of the trap.…”

Section: Introductionmentioning

confidence: 99%

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Amplitude scaling of asymmetry-induced transport

Eggleston¹,

Carrillo²

2002

AIP Conference Proceedings

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Abstract. Our initial experiments on asymmetry-induced transport in non-neutral plasmas found the radial particle flux at small radii to be proportional to 02, where 0. is the applied asymmetry amplitude. Other researchers, however, using the global expansion rate as a measure of the transport, have observed a €1 scaling when the rigidity (the ratio of the axial bounce frequency to the azimuthal rotation frequency) is in the range one to ten. In an effort to resolve this discrepancy, we have extended our measurements to different radii and asymmetry frequencies. Although the results to date are generally in agreement with those previously reported (0' scaling at low asymmetry amplitudes falling off to a weaker scaling at higher amplitudes), we have observed some cases where the low amplitude scaling is closer to q1. Both the 0' and 0' cases, however, have rigidities less than ten. Instead, we find that the q5l cases are characterized by an induced flux that is comparable in magnitude but opposite in sign to the background flux. This suggests that the mixing of applied and background asymmetries plays an important role in determining the amplitude scaling of this transport.

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“…Thus, it now appears likely that most of the (L/B) −2 lifetime scalings from "background asymmetries" [6] can be given interpretation in terms of the (partially) known scalings for TPM transport. The measurements of transport from applied electric and magnetic asymmetries [7,8,9, 10] also should be compared to TPM predictions. "Anomalous" damping of diocotron modes [7,11,12] is almost certainly related to TPM effects, since TPM damping scales as B −3 .…”

Section: Introductionmentioning

confidence: 99%

Trapped-Particle-Mediated Damping and Transport

Driscoll¹,

Kabant︠s︡ev²,

Hilsabeck³

et al. 2003

AIP Conference Proceedings

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Abstract. Weak axial variations in B(z) or φ (z) in Penning-Malmberg traps cause some particles to be trapped locally. This causes a velocity-space separatrix between trapped and passing populations, and collisional separatrix diffusion then causes mode damping and asymmetry-induced transport. This separatrix dissipation scales with collisionality as ν 1/2 , so it dominates in low collisionallity plasmas. The confinement lifetime in the "CamV" apparatus was dominated by a weak magnetic ripple with δ B/B ∼ 10 −3 , and it appears likely that the ubiquitous (L/B) −2 lifetime scalings and other applied asymmetry scalings represent similar TPM effects. TPM transport will limit the containment of large numbers of positrons orps, since TPM loss rates generally scale as total charge Q 2 , independent of length.

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Two Regimes of Asymmetry-Induced Transport in Non-neutral Plasmas

Cited by 46 publications

References 27 publications

Decay of the Diocotron Rotation and Transport in a New Low-Density Asymmetry-Dominated Regime

Decay of the Diocotron Rotation and Transport in a New Low-Density Asymmetry-Dominated Regime

Amplitude scaling of asymmetry-induced transport

Trapped-Particle-Mediated Damping and Transport

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