Role of particle size and gas pressure on the nonlinear oscillatory behavior of a dust particle in a direct current discharge

Abstract

Experimental and theoretical studies were conducted to simultaneously study the role of particle size and gas pressure on nonlinear behavior of dust oscillations in a plasma. Oscillation spectra were experimentally obtained by using four different sized (1.5, 2, 3, and 4 m) particles at 250 mTorr, which is high pressure compared to previously reported works. The measured results were in good agreement with theoretical calculations based on a self-consistent collisional plasma model and a parametric dust oscillation model. In addition, particle size and gas pressure dependence of force profile and oscillation spectrum was investigated by numerical calculation in order to understand the role of particle size and pressure separately. It is concluded that occurrence of the subharmonic resonance and the net trapping force profile are mainly determined by particle size while gas pressure is mostly responsible for the superharmonic resonance and hysteresis.

Optical Properties of Terahertz Wave Emitter Fabricated by Using CdxZn1-xTe Single Crystals

“…An experiment on the gas pressure dependence was also performed, and the result was in good agreement with the numerical calculations given in [7].…”

“…Also, m i , λ i , φ, n e , T e and k denote ion mass, ion mean free path, electrostatic potential, electron density, electron temperature and Boltzmann constant, respectively. Equations (1)-(4) were calculated following the procedure in [7]. The dust particle charge was calculated by considering the electron current and the ion current flowing into the particle.…”

“…Using the potential and the charge calculated from equations (1)- (6), the electrostatic force acting upon each particle was obtained, and the ion drag force was calculated by following equation (7) of [7] written as…”

“…It was also demonstrated that the observed nonlinearities could be related to a position dependent charge variation of micro-spheres [3]. The particle size dependence of the oscillation spectrum was investigated experimentally to understand the role of particle size, and the pressure dependence of the oscillation spectrum was also studied by numerical simulation [7].…”

Electron temperature and pressure dependences of nonlinear phenomena in dust particle oscillation in dc plasmas

“…Because the experimental conditions in this paper were nearly the same as those in [7], it was assumed that (n e ) mod = 0.6n e corresponded to the maximum V wire (V wire = +10 V) and (n e ) mod = 1.4n e corresponded to the minimum V wire (V wire = −10 V), using the results from [7]. Figure 4 shows the calculated F int (z) at V cath = 280-350 V. The direction of the net force is toward the equilibrium position, z 0 .…”