STM-D-0987Paper2007Published and peer-reviewed

Space charge neutralization in inertial electrostatic confinement plasmas

E. G. Evstatiev · R. A. Nebel · L. Chacón · J. Park · G. Lapenta

Abstract and summary · read the original at the source · none found

In one page

An inertial electrostatic confinement machine holds a fusion plasma with voltage instead of magnets: ions are pulled inwards towards a point, overshoot it, fall back through it, and keep doing that. One way to build the pull is to inject electrons and let their negative charge make the well. But a cloud of electrons pushes hard on itself, and that self-repulsion — its space charge — is what caps how dense the core can get. Evstatiev and colleagues at Los Alamos National Laboratory develop a new formalism for cancelling it, and their answer splits in two. If the plasma is made to oscillate, which is how compression is won, then holding the charge neutralised while also holding the background potential in the parabolic shape the scheme needs puts a firm ceiling on how far the core can be squeezed. If the plasma is run steady instead, no such ceiling appears, and neutralisation still holds even as the plasma goes quasineutral.

Why it matters hereChapter 12 needs a small source of very large energy, and the electrostatic machines are the least expensive route anyone has to one; this paper is the design rule that decides how such a machine should be run, because it says which operating mode pays for compression with a ceiling and which does not. Chapter 9 keeps the record of oscillating and self-organising plasma structures held in a laboratory, and the breathing plasma treated here is one of them.

What it claims

01Space charge neutralization is the major issue for inertial electrostatic confinement devices that make their confining potential well by injecting electrons — the injected electron cloud’s own repulsion is what limits the machine.Abstract, first sentence
Published and peer-reviewed
02The paper develops a new formalism that allows that neutralization to occur, and it covers both operating modes — plasmas that oscillate and plasmas held in steady state.Abstract, second sentence
Published and peer-reviewed
03For oscillating plasmas the results give limits on how much compression can be achieved while simultaneously maintaining space charge neutralization and the parabolic background potential the oscillating scheme depends on — compression and neutralization are in competition in that mode.Abstract, third sentence
Published and peer-reviewed
04For steady-state plasmas there are no such limits, and space charge neutralization can be achieved even when the plasma becomes quasineutral, that is even when the ion and electron densities have come into balance.Abstract, fourth sentence
Published and peer-reviewed
05The design question this poses for anyone building one of these machines is which mode to run: oscillation buys compression but caps it, steady state removes the cap, and the measurement that settles it is whether a steady-state electron-injected device holds its neutralization all the way into the quasineutral, high-density regime.Abstract, third and fourth sentences read together
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Read it · abstract

Abstract

A major issue for electron injected inertial electrostatic confinement (IEC) devices is space charge neutralization. A new formalism is developed that will allow this neutralization to occur for both oscillating and steady-state IEC plasmas. Results indicate that there are limits on the amount of compression that can be achieved by oscillating plasmas while simultaneously maintaining space charge neutralization and parabolic background potential. For steady-state plasmas, there are no such limits and space charge neutralization can be achieved even when the plasma becomes quasineutral.

The way in

https://doi.org/10.1063/1.2711173Published as Physics of Plasmas volume 14, article 042701, April 2007, copyright AIP Publishing, with no Creative Commons statement on the record. A free copy was looked for and not found on 2026-09-08. The publisher’s own PDF, which Unpaywall marks bronze rather than licensed, was refused to this fetch; the Department of Energy’s Office of Scientific and Technical Information holds only a bibliographic record, OSTI 20974937, with no full-text or accepted-manuscript attachment, so there is no Los Alamos author copy to read and nothing here can be treated as a United States Government work; a Zenodo item listed for the DOI by OpenAIRE answered access-restricted. The sheet therefore stays abstract-only and is written from the abstract and the bibliographic record — journal, volume, page, date and the authors’ Los Alamos National Laboratory affiliation — which is why every locator points to a sentence of the abstract rather than to a section of the paper. The abstract below is the publisher-deposited text as OSTI carries it, verbatim; the copy in this site’s own fetch record had lost its parentheses and its spaces between sentences to a character-encoding fault, and that is the only difference. Author initials are left as the publisher’s record gives them. Companion sheets: ion kinetics in an inertial electrostatic confinement device at /library/stm-0b806244cb, the cylindrical device discharge study at /library/stm-218a859c1b, deuterium anions in these devices at /library/stm-27b0684846, and the Defense Intelligence Agency reference document on the whole approach at /library/stm-cac9786426.

How to cite it

E. G. Evstatiev, R. A. Nebel, L. Chacón, J. Park, G. Lapenta (2007) Space charge neutralization in inertial electrostatic confinement plasmas. doi:10.1063/1.2711173

Where it sits in the curriculum

Lattice confinement fusion Plasmoids, charge clusters and the orbs