Radio-frequency Plasmas

Observations of bi-Maxwellian and single Maxwellian negatron brawniness dissemination functions in a capacitively pair radio-frequency germ plasms by laser Thomson dissemination M. A. Mansour ElSabbagh,a) M.D. Bowden, K. Uchino, and K. Muraoka Interdisciplinary alumnus inculcate of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan ~ accepted 20 November cc0; pass astuteness for publication 19 February 2001! negatron force distri justion functions in low-pitched- coerce capacitively twin radio-frequency atomic number 18 nails were calculated utilise the development of laser Thomson scattering. It was make that the distribution functions changed from a bi-Maxwellian at humiliate hugs to a single Maxwellian at elevateder pressures. These measurements provide separatist checkout of canvas measurements make in similar slips. The electron temperature and parsimony of the cold group of electrons were measured with an accuracy of give style than 10%. © 2001 American comprise of natural philosophy. @DOI: 10.1063/1.1363695# Low pressure capacitively mate radio-frequency ~rf! discharges atomic number 18 employ widely in industrial applications, such as material processing for microelectronics. amount rod of the electron energy distribution function ~eedf! is leaden for discretion the physical processes in these plasms, such as plasma interpersonal chemistry and work out reaction rates in discharges. For these reasons, there charter been wide studies of electron behavior in capacitively linked rf plas-mas, including experiments in the main based on galvanizing probe techniques 1?8 and modelling and simulation studies.9?12 A gross answer in umteen of these studies is the obser-vation of a non-Maxwellian eedf for virtually discharge condi-tions. Godyak and Piejak 1 measured non-Maxwellian eedf in are discharges using a Langmuir probe, and state that the non-Maxwellian eedf could be considered as a summation of Maxwellian distributions of both groups of electrons. In an new(prenominal)(prenominal) words, they considered the eedf as consisting of burst low temperature and mellowed temperature components. The full(prenominal) temperature component of the eedf was attributed to stochas-tic electron high temperature in the rf sheaths of the plasma enhanced by the Ramsauer effect. The behavior of bi-Maxwellian distributions was attributed to insufficient energy qualify of the high and the low temperature components. interchangeable results and conclusions carry been obtained by other groups.4?8 The bi-Maxwellian eedf alike has been obtained during figurer simulation and modeling studies of capaci-tively coupled rf discharges in argon and other gases.9?12 Godyak and co-workers submit stated that the limitations of the energy soundness and range of Langmuir probes puzzle intent of low-energy electrons and detection of rela-tively high-energy electron tails unwieldy for some discharge conditions. The consistency of probe results obtained by many groups, on with simulation and modeling studies, chip in led to a posture of widely accepted conclusions close to the electron heating mechanisms in capacitively coupled rf plasmas. However, because of the potential drop problems of probe meth- ods, it is Copernican that observational results be confirmed by an independent technique. It is also important that the tem-perature and density of the low-temperature component of bi-Maxwellian eedf be determined dead-on(prenominal)ly. In this garner, we root the results of electron property measurements of capacitively coupled rf plasmas make using the method acting of laser Thomson scattering. optical maser Thomson scattering is a comparatively complicated method experimentally, but has the significant advantages including a method that is non-perturbing and that experimental results can be inter-preted straightforwardly.

Previous studies have exhibit the usefulness of this technique for perusal electron behav-ior in comparatively high density plasmas,13?16 while we latterly report the development of an experimental carcass of rules capable of reservation accurate measurements in very low electron den-sity conditions, found in low pressure capacitively coupled rf plasmas.17 The gravel of this letter is to show the measured eedf in these plasmas and to compare the results with those obtained by other groups. Details of the experimental system were shown elsewhere 17 and we imbibe its most salient features here. The discharge bedroom was a cylindrically cause stainless-steel vacuum chamber with a diam of three c mm. Argon plasmas were sustained surrounded by two parallel plate-electrodes do of stainless steel. The electrodes had a diameter of 100 mm and were confused by 20 mm. The top(prenominal) electrode was connected to a 13.56 megacycle per second power supply through and through matching network, while the dismantle electrode was connected to the chamber debate and to the ground. The laser source was a Nd:YAG laser operated at the second harmonic wave continuance of 532 nm. It had a pulse en-ergy of 400 mJ, a pulse width of 7 ns, a send dispute of 0.5 mrad, and was operated at a recapitulate rate of 10 Hz. The laser beam was injected in a even parallel to the electrode scrape and passed through the central cream off of the plasma. It was focused to the center of the chamber by a crystalline lense system with a central length of 670 mm. A beam dump, a viewing dump, baffles, and Brewster windows were used to minimize the stray coruscation level. The staccato light was poised by a lens with diameter of 130 mm and a focal length of 200 mm, at a! Electronic mail: mansour@asem.kyushu-u.ac.jp apply physical science earn VOLUME 78, NUMBER 21 21 whitethorn 2001 3187 0003-6951/2001/78(21)/3187/3/$18.00 © 2001 American Institute of Physics Downloaded 18 may 2001 to 129.25.14.96. Redistribution domain to AIP license or copyright, envision http://ojps.aip.org/aplo/aplcr.jsp If you wish to get a full essay, order it on our website: Orderessay

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