Adiabatic Expansion of Electron Gas in a Magnetic Nozzle

Kazunori Takahashi, Christine Charles, Rod Boswell, Akira Ando

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)

Abstract

A specially constructed experiment shows the near perfect adiabatic expansion of an ideal electron gas resulting in a polytropic index greater than 1.4, approaching the adiabatic value of 5/3, when removing electric fields from the system, while the polytropic index close to unity is observed when the electrons are trapped by the electric fields. The measurements were made on collisionless electrons in an argon plasma expanding in a magnetic nozzle. The collision lengths of all electron collision processes are greater than the scale length of the expansion, meaning the system cannot be in thermodynamic equilibrium, yet thermodynamic concepts can be used, with caution, in explaining the results. In particular, a Lorentz force, created by inhomogeneities in the radial plasma density, does work on the expanding magnetic field, reducing the internal energy of the electron gas that behaves as an adiabatically expanding ideal gas.

Original languageEnglish
Article number045001
JournalPhysical review letters
Volume120
Issue number4
DOIs
Publication statusPublished - 2018 Jan 26

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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