Title: Future beam experiments in the magnetosphere with plasma contactors: How do we get the charge off the spacecraft?

Abstract

Abstract The idea of using a high‐voltage electron beam with substantial current to actively probe magnetic field line connectivity in space has been discussed since the 1970s. However, its experimental realization onboard a magnetospheric spacecraft has never been accomplished because the tenuous magnetospheric plasma cannot provide the return current necessary to keep spacecraft charging under control. In this work, we perform Particle‐In‐Cell simulations to investigate the conditions under which a high‐voltage electron beam can be emitted from a spacecraft and explore solutions that can mitigate spacecraft charging. The electron beam cannot simply be compensated for by an ion beam of equal current, because the Child‐Langmuir space charge limit is violated under conditions of interest. On the other hand, releasing a high‐density neutral contactor plasma prior and during beam emission is critical in aiding beam emission. We show that after an initial transient controlled by the size of the contactor cloud where the spacecraft potential rises, the spacecraft potential can settle into conditions that allow for electron beam emission. A physical explanation of this result in terms of ion emission into spherical geometry from the surface of the plasma cloud is presented, together with scaling laws of the peak spacecraft potentialmore » varying the ion mass and beam current. These results suggest that a strategy where the contactor plasma and the electron beam operate simultaneously might offer a pathway to perform beam experiments in the magnetosphere.« less

Authors:

Delzanno, G. L. ^[1]; Borovsky, J. E. ^[2]; Thomsen, M. F. ^[3]; Moulton, J. D. ^[1]; MacDonald, E. A. ^[4]

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+ Show Author Affiliations

1. Theoretical Division Los Alamos National Laboratory Los Alamos New Mexico USA
2. Space Science Institute Boulder Colorado USA, AOSS University of Michigan Ann Arbor Michigan USA
3. Intelligence and Space Research Division Los Alamos National Laboratory Los Alamos New Mexico USA
4. Nasa Goddard Greenbelt Maryland USA

Publication Date:

Fri May 22 00:00:00 EDT 2015

Sponsoring Org.:

USDOE

OSTI Identifier:

1402185

Resource Type:

Publisher's Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Space Physics

Additional Journal Information:

Journal Name: Journal of Geophysical Research. Space Physics Journal Volume: 120 Journal Issue: 5; Journal ID: ISSN 2169-9380

Publisher:

American Geophysical Union (AGU)

Country of Publication:

United States

Language:

English