EFFECTS OF ARGON ATOMS IN EXCITED STATES ON PROPERTIES OF ARGON-ACETYLENE DUSTY PLASMA

It is studied how dissociation and ionization of acetylene molecules in their collisions with argon atoms in excited states Ar* may affect properties of argon-acetylene plasma with growing inside of plasma volume dust particles. The study is carried out using a volume-averaged model. To analyze the effects of Ar* atoms on the electron and ion densities, the effective electron temperature and the densities of radical and nonradical neutral species, the values of ionization and dissociation rates for collisions of acetylene molecules with Ar* atoms are varied in numerical calculations. It is found that the collisions of Ar* atoms with acetylene molecules affect essentially the argon-acetylene dusty plasma.

Piezoelectric interaction in controlling the effective electron temperature and the non-ohmic mobility characteristics in GaN and other III–V compounds at low lattice temperature

In a compound semiconductor that lacks inversion symmetry, the free electrons interact simultaneously with the piezoelectric and acoustic phonons. This combined interaction principally controls the electrical transport at low lattice temperatures. Again, at low temperatures, the electrons in some of the compounds may be significantly perturbed for comparatively low fields, say, even for a fraction of a Vcm−1 or so, which effectively seems to be high enough, and the material exhibits electrical nonlinearity. Such a perturbed ensemble then attains a field dependent effective electron temperature Te, which exceeds the lattice temperature TL. The relative importance of the piezoelectric interaction in controlling the field dependence of the effective electron temperature, and therefrom, the non-ohmic mobility characteristics have been analyzed here under the condition of low lattice temperature. The numerical results obtained for InSb, InAs, and GaN are studied in detail. When compared with the experiments, the results here seem to give the same qualitative picture with respect to the variation of the non-ohmic mobility with the electric field for the indium compounds. The results, being interesting, stimulate further work in the same field.

Dust and plasma properties measured using two confined particles

We consider two isolated, interacting dust particles confined in plasma. Measurements of normal mode frequencies are used to determine the dust charge, the Debye shielding length and the anisotropy of the confining potential well. For dust particles confined near the sheath edge, the vertical electric field and an effective electron temperature are also determined. This method is used to characterize the sheath above a short rectangular trench in the powered electrode of a radio-frequency discharge.

Effect of q-non-extensive distribution of electrons on the plasma sheath floating potential

In this paper, a collisionless unmagnetized plasma sheath consisting of electrons following non-extensive q-distribution, and cold mobile inertial ions is studied in the stationary state. In this type of plasma with non-Maxwellian electron distribution (Tsallis statistical mechanics), the effective electron temperature (Te, eff) and electron screening temperature (Te,*) are evaluated. The other plasma sheath phenomena such as the Bohm sheath criterion, Debye shielding, floating potential, and sheath length are investigated in the presence of q-non-extensive velocity-distributed electrons. It is observed that above-mentioned phenomena depend significantly on the non-extensive parameter q.

Evidence of enhanced effective hot electron temperatures in ultraintense laser-solid interactions due to reflexing

It is shown that the effective hot electron temperature, Thot, associated with the energetic electrons produced during the interaction of an ultra-intense laser with thin solid targets is dependent on the thickness of the target. We report the first direct experimental observations of electron energy spectra obtained from laser-solid interactions that indicates the reflexing of electrons in thin targets results in higher electron temperatures than those obtained in thick target interactions. This can occur for targets whose thickness, xt, is less than about half the range of an electron at the energy associated with the initial effective electron temperature, provided the laser pulse length is at least cτp > 2xt. A simple theoretical model that demonstrates the physical mechanism behind this enhanced heating is presented and the results of computer simulations are used to verify the model.

Nonlinear transport and fluctuation characteristics of doped semiconductors

Fluctuation phenomena in doped n-type GaAs, at moderate applied electric fields being influenced by interelectron scattering, are interpreted in terms of effective electron temperature. Electron Fick’s diffusion coefficients in longitudinal and transfer direction are estimated.