Ion acceleration in Ar-Xe and Ar-He plasmas. I. Electron energy distribution functions and ion composition

Biloiu, Ioana A.; Scime, Earl E.
November 2010
Physics of Plasmas;Nov2010, Vol. 17 Issue 11, p113508
Academic Journal
Electron energy distribution functions (eedf), ion production, and ion composition are studied in Ar-Xe and Ar-He expanding helicon plasmas. It was found that under the conditions of constant total flow rate, Xe, in addition to Ar, changes the eedf from Maxwellian-like to Druyvesteyn-like with a shortening of the high energy tail at ∼15 eV. The electron temperature exponentially decreases from ∼7 eV in pure Ar plasma to ∼4 eV in pure Xe plasma. Xenon ions dominate the ion population for Xe filling fractions greater than 10%. The plasma density increases by ∼15% with increasing Xe fraction. For an Ar-He plasma, increasing the helium fraction increases the electron temperature from ∼7 eV in pure Ar plasma to ∼14 eV for a He filling fraction of 80%. The plasma density drops by more than three orders of magnitude from 1.14×1011 cm-3 to 6.5×107 cm-3. However, the inferred ion densities indicate that even at a helium fraction of 80%, argon ions significantly outnumber helium ions.


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