Langmuir paradox revisited

Electron energy distribution functions (EEDF) have been measured in the positive column of dc discharges under the condition of the Langmuir paradox (1 and 3 mTorr of argon gas) using a high resolution probe measurement system developed by the authors. An essential deviation of the measured EEDFs from Maxwellian distributions was found for both, slow and for fast electrons. The low energy peaks found in the measured non-Maxwellian EEDFs are attributed to non-local electron kinetics in the axially non-uniform electric field caused by standing striations. Similarly, in rf capacitive and inductive discharges, the formation of the low energy peak is a result of spatially localized electron heating combined with trapping of low energy electrons outside of the heating zone.

[1]  Y. Golubovskii,et al.  Advances in the study of striations in inert gases , 2014 .

[2]  S. Mayorov.  On the electron energy distribution in the gas discharge positive column: Langmuir paradox , 2013 .

[3]  Valery Godyak,et al.  Ferromagnetic enhanced inductive plasma sources , 2012 .

[4]  L. Tsendin.  Nonlocal electron kinetics in gas-discharge plasma , 2010 .

[5]  Vladimir Kolobov,et al.  Striations in rare gas plasmas , 2006 .

[6]  V. Godyak,et al.  Nonequilibrium EEDF in gas discharge plasmas , 2006, IEEE Transactions on Plasma Science.

[7]  A. Kudryavtsev,et al.  Mechanisms for formation of the electron distribution function in the positive column of discharges under Langmuir-paradox conditions , 1999 .

[8]  Vladimir Kolobov,et al.  EFFECT OF COLLISIONLESS HEATING ON ELECTRON ENERGY DISTRIBUTION IN AN INDUCTIVELY COUPLED PLASMA , 1998 .

[9]  Parker,et al.  Comparison of Monte Carlo simulations and nonlocal calculations of the electron distribution function in a positive column plasma. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[10]  Godyak,et al.  Abnormally low electron energy and heating-mode transition in a low-pressure argon rf discharge at 13.56 MHz. , 1990, Physical review letters.

[11]  N. Twiddy,et al.  Electron energy distributions in the low-pressure mercury-vapour discharge: the Langmuir paradox , 1968, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[12]  S. Self,et al.  On the Low-pressure Mercury-vapour Discharge Mechanism and the Origins of Langmuir's Paradox† , 1965 .

[13]  D. Gabor,et al.  Langmuir's Paradox , 1955, Nature.

[14]  Harrison J. Merrill,et al.  Electron Scattering and Plasma Oscillations , 1939 .

[15]  I. Langmuir.  The Interaction of Electron and Positive Ion Space Charges in Cathode Sheaths , 1929 .

[16]  I. Langmuir.  Scattering of Electrons in Ionized Gases , 1925 .