Poloidal<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>E</mml:mi><mml:mo>×</mml:mo><mml:mi>B</mml:mi></mml:math>Drift Used as an Effective Rotational Transform to Achieve Long Confinement Times in a Toroidal Electron Plasma

Stoneking, M. R.; Growdon, M. A.; Milne, M. L.; Peterson, Ricardo

doi:10.1103/physrevlett.92.095003

Cited by 26 publications

(19 citation statements)

References 25 publications

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“…poloidal mode number observed in Penning traps [22] and pure toroidal field traps [23,24]. However, in these traps, parallel force balance is not violated, as they do not have magnetic surfaces or any rotational transform.…”

Section: Ion Resonant Instabilitiesmentioning

confidence: 96%

Dynamics of Electron-Rich Plasmas in the CNT Stellarator

Pedersen

Berkery

Boozer

et al. 2008

Plasma and Fusion Research

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Pure electron plasmas and electron plasmas with a finite ion fraction have been studied in the Columbia Nonneutral Torus (CNT) since the end of 2004. Results from the first three years of operation are summarized. Stable, small Debye length pure electron plasmas are routinely created, and have confinement times up to 20 msec. The confinement is limited by radial transport caused by internal rods, as well as electron-neutral collisions. The neutral driven transport rate is indicative of poor particle orbits in CNT, despite the strong radial electric field. Numerical simulations shed light on this issue, demonstrating the detrimental effects of variations in the electrostatic potential on a magnetic surface. With the installation of a magnetic surface conforming electrostatic boundary and the transition to external diagnostics, significantly longer confinement times should be possible. Also presented are observations of sudden confinement jumps that have a hysteretic behavior, and observations of an ion driven instability.

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Section: Ion Resonant Instabilitiesmentioning

confidence: 96%

Dynamics of Electron-Rich Plasmas in the CNT Stellarator

Pedersen

Berkery

Boozer

et al. 2008

Plasma and Fusion Research

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“…(19), with the polarization energy associated with the radial permittivity of the plasma ε ⊥ . The amount of energy needed to construct a radial electric field E a is then given by…”

Section: Energy Content Of Radial and Poloidal Fieldsmentioning

confidence: 99%

“…The impact of electric rotation in various toroidal configurations was also analyzed 13 . Electric rotation to overcome drifts was likewise analyzed, both theoretically and experimentally, within the context of particle accelerators [14][15][16][17] and non-neutral plasma confinement [18][19][20] .…”

Section: Introductionmentioning

confidence: 99%

Efficiency of wave-driven rigid body rotation toroidal confinement

2017

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The compensation of vertical drifts in toroidal magnetic fields through a wave-driven poloidal rotation is compared to compensation through the wave driven toroidal current generation to support the classical magnetic rotational transform. The advantages and drawbacks associated with the sustainment of a radial electric field are compared with those associated with the sustainment of a poloidal magnetic field both in terms of energy content and power dissipation. The energy content of a radial electric field is found to be smaller than the energy content of a poloidal magnetic field for a similar set of orbits. The wave driven radial electric field generation efficiency is similarly shown, at least in the limit of large aspect ratio, to be larger than the efficiency of wave-driven toroidal current generation.

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“…As the magnetic field increases, the radius of the cyclotron orbit decreases due the conservation of angular momentum. Therefore, The frequency of collisions, f , of a single electron in a cycle of the magnetron motion, f ∝ r c r m (8) where r c and r m are respectively, the radii corresponding to the (modified) cyclotron and magnetron motions (Fig. 2).…”

Section: Theorymentioning

confidence: 99%

“…Inhomogeneity in the external magnetic fields in case of Penning traps is an additional perturber and contributes to loss of ions [1,6]. Confinement times of long durations are realized for high precision measurements after incorporating techniques that restrict these perturbations to minimum levels [2,7,8]. In a series of pioneering experiments [9,10] electron confinement in cylindrical Penning traps (CPT) have been investigated.…”

Section: Introductionmentioning

confidence: 99%

Dependence of the confinement time of an electron plasma on the magnetic field in a quadrupole Penning trap

et al. 2017

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A quadrupole Penning trap is used to confine electrons in weak magnetic fields. Perturbations due to space charge and imperfections in the trap geometry, as well as collisions with the background gas molecules, lead to loss of the electrons from the trap. We present in this work the results on measurements of the electron confinement time and its dependence on the magnetic field in a quadrupolar Penning trap. We describe a method to measure the confinement time of an electron cloud under weak magnetic fields (0.01 T -0.1 T). This time is found to scale as τ ∝ B 1.41 in variance with the theoretically expected confinement time that scales as τ ∝ B 2 for trapped electrons that are lost through collisions with the neutrals present in the trap. A measurement of the expansion rate of the electron plasma in the trap through controlled variation of the trap voltage, yields expansion times that depend on the energy of escaping electrons. This is found to vary in our case in the scaling range B 0.32 to B 0.43 . Distorting the geometry of the trap, results in a marked change in the confinement time's dependence on the magnetic field. The results indicate that the confinement time of the electron cloud in the trap is limited by both, effects of collisions and perturbations that result in the plasma loss through expansion in the trap.

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PoloidalE×BDrift Used as an Effective Rotational Transform to Achieve Long Confinement Times in a Toroidal Electron Plasma

Cited by 26 publications

References 25 publications

Dynamics of Electron-Rich Plasmas in the CNT Stellarator

Dynamics of Electron-Rich Plasmas in the CNT Stellarator

Efficiency of wave-driven rigid body rotation toroidal confinement

Dependence of the confinement time of an electron plasma on the magnetic field in a quadrupole Penning trap

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