Reduction of electron heating by magnetizing ultracold neutral plasma

Tiwari, Sanat Kumar

doi:10.1063/1.5013320

Cited by 16 publications

(14 citation statements)

References 46 publications

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“…All of the analysis in this work was done for non-magnetized plasma. It has been suggested based on simulations that applying a strong magnetic field reduces the magnitude of disorder-induced heating, at least in UCP (Tiwari & Baalrud 2018). In addition, we have treated only a single fixed charge state.…”

Section: Discussionmentioning

confidence: 99%

Temperature separation under compression of moderately coupled plasma

Fetsch,

Foster,

Fisch

2023

J. Plasma Phys.

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In moderately coupled plasmas, a significant fraction of the internal energy resides in electric fields. As these plasmas are heated or compressed, the shifting partition of energy between particles and fields leads to surprising effects, particularly when ions and electrons have different temperatures. In this work, quasi-equations of state (quasi-EOS) are derived for two-temperature moderately coupled plasma in a thermodynamic framework and expressed in a simple form. These quasi-EOS readily yield expressions for correlation heating, in which heating of the electrons causes a rapid increase in ion temperature even in the absence of collisional energy exchange between species. It is also shown that, remarkably, compression of moderately coupled plasma drives a temperature difference between electrons and ions, even when the species start at equal temperatures. These additional channels for ion heating may be relevant in designing ignition schemes for inertial confinement fusion.

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Section: Discussionmentioning

confidence: 99%

Temperature separation under compression of moderately coupled plasma

Fetsch,

Foster,

Fisch

2023

J. Plasma Phys.

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“…"Softening" the Coulomb potential with the α term mitigates this problem. 24 Given the importance of Rydberg atoms in this investigation, the possible distortion of Rydberg populations through the addition of the α term is a concern. We chose α to be equal to just under 2% of a WS .…”

Section: Numerical Simulation Of Electron Center-of-mass Oscillation ...mentioning

confidence: 99%

Many-body collision contributions to electron momentum damping rates in a plasma influenced by electron strong coupling

2020

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Experimental studies of electron-ion collision rates in an ultracold neutral plasma (UNP) can be conducted through measuring the rate of electron plasma oscillation damping. For sufficiently cold and dense conditions where strong coupling influences are important, the measured damping rate was faster by 37% than theoretical expectations [W. Chen, C. Witte, and J. Roberts, Phys. Rev. E 96, 013203 (2017)]. We have conducted a series of numerical simulations to isolate the primary source of this difference. By analyzing the distribution of electron velocity changes due to collisions in a molecular dynamics simulation, examining the trajectory of electrons with high deflection angle in such simulations, and examining the oscillation damping rate while varying the ratio of two-body to three-body electron-ion collision rates, we have found that the difference is consistent with the effect due to many-body collisions leading to bound electrons. This has implications for other electron-ion collision related transport properties in addition to electron oscillation damping.In strongly coupled plasmas, the average nearestneighbor Coulomb potential energy for one or more types of particles is comparable to or exceeds the average kinetic energy of that type of particle. As a result, spatial correlations between plasma particles become significant and many common assumptions used in plasma theory break down. [1][2][3][4][5][6][7] In contrast to weakly-coupled plasmas where collisions can be treated as long-range binary scattering events, in strongly-coupled plasmas, many-body effects become increasingly significant. These manybody effects can be treated theoretically through, for instance, using simulations to create phenomenological extensions of binary collision theory into the stronglycoupled regime, 8 or through creating an effective potential that incorporates many-body effects into interparticle effective potentials. 9However, in strongly-coupled plasmas with electrons and ions (as opposed to one-component plasmas), threeand more-body collisions can result in electrons becoming bound to one or more ions in the plasma, forming a Rydberg atom or an electron bound to a small number of ions. [10][11][12][13] In this article, we show that such manybody collisions provide a substantial contribution to the electron average momentum damping rate in plasmas where electron strong coupling is significant. For such strongly coupled plasmas, these many-body-to-boundstate (MBTBS) collisions would be expected to be relevant for other collision-related properties as well, such as stopping power, 14,15 thermalization rates, 16 and other transport properties. 17This investigation of MBTBS collision contributions to the average electron momentum damping rate was motivated by studies of electron oscillation damping in an ultracold neutral plasma (UNP). 3 In that work, electron center-of-mass oscillations were induced by imparting an impulse acceleration in one direction to the electrons' velocities. The electrons' center-of-mass then oscill...

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“…A prominent laboratory example is non-neutral plasmas 32 , such as the plasmas in antimatter traps 33 , which can reach very strongly magnetized conditions. A host of other experiments may reach strongly magnetized conditions in the near future, including ultracold neutral plasmas [34][35][36][37] , dusty plasmas [38][39][40] , plasmas in highly compressed magnetized inertial confinement fusion experiments 41,42 , and in intense laser-matter interaction experiments 43 . Regimes in which electrons reach a marginal level of strong magnetization (β e ∼ 1) are more common, including electrons in tokamak experiments 44 .…”

Section: Introductionmentioning

confidence: 99%

dc electrical conductivity in strongly magnetized plasmas

Baalrud,

Lafleur

2021

Preprint

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A generalized Ohm's law is derived to treat strongly magnetized plasmas in which the electron gyrofrequency significantly exceeds the electron plasma frequency. The frictional drag due to Coulomb collisions between electrons and ions is found to shift, producing an additional transverse resistivity term in the generalized Ohm's law that is perpendicular to both the current (J) and the Hall (J × B) direction. In the limit of very strong magnetization, the parallel resistivity is found to increase by a factor of 3/2, and the perpendicular resistivity to scale as ln(ω ce τ e ), where ω ce τ e is the Hall parameter. Correspondingly, the parallel conductivity coefficient is reduced by a factor of 2/3, and the perpendicular conductivity scales as ln(ω ce τ e )/(ω ce τ e ) 2 . These results suggest that strong magnetization significantly changes the magnetohydrodynamic evolution of a plasma.

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Reduction of electron heating by magnetizing ultracold neutral plasma

Cited by 16 publications

References 46 publications

Temperature separation under compression of moderately coupled plasma

Temperature separation under compression of moderately coupled plasma

Many-body collision contributions to electron momentum damping rates in a plasma influenced by electron strong coupling

dc electrical conductivity in strongly magnetized plasmas

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