Normal regime of the weak-current mode of an rf capacitive discharge

Abstract

This paper studies the normal and abnormal regimes of a weak-current rf discharge in ammonia, nitrogen, hydrogen and N 2 O for the rf electric field frequencies of 13.56 and 27.12 MHz. We reveal that only the abnormal regime of burning is observed at low pressures when the current growth is accompanied by an rf voltage increase while the surface of the electrodes is completely covered with the discharge. The normal regime occurs at higher gas pressures when the current growth is due to the increase in the surface area occupied by the discharge on the electrodes. The discharge burns in the abnormal mode after the surface of the electrodes is completely covered with the discharge. We demonstrate that the normal current density is directly proportional to the gas pressure and it depends approximately on the square of the rf electric field frequency. We present an analytical model for two limiting cases: constant free path length and constant mobility of positive ions furnishing a satisfactory description of the experimental data.

Applicability of Child–Langmuir collision laws for describing a dc cathode sheath in N2O

“…Our data for large pressure values agree with the conclusion of paper (Lisovskiy et al 2013), where it was demonstrated that the normal current density effect in the rf discharge in the N 2 O gas is best described by the model assuming the constant mean free path of N 2 O + ions in the near-electrode sheath. Note that conventionally the normal mode is observed in the rf discharge in N 2 O at the pressure values order of or above 1 Torr.…”

Synthesis of Nanoparticles and Theoretical Model of Their Retention in Plasma of RF Capacitive Discharge with Vertically Arranged Electrodes in Acetylene

“…The RF capacitive discharge consists of two near-electrode sheaths (in which the positive space charge predominates), as well as a quasi-neutral plasma in between them (Figure ). , …”

“…The main difference between the cases of horizontal and vertical electrodes is that the voltage drop in the near-electrode sheath (its constant component) can reach hundreds and even thousands of volts, ,, while the dielectric walls of the discharge tube are under a floating potential relative to the plasma, the sign of which is usually negative, and the value is usually 3–5 electron temperatures and does not exceed 15–20 V. , Consequently, only relatively small NPs can be retained in the discharge plasma with vertically arranged electrodes (in the experiments described above, we saw particles with a typical diameter of up to about 400–600 nm), while larger particles must overcome a small electric field force and fall onto the tube wall. With horizontal electrodes, gravity is opposed by a much stronger electric field in the near-electrode sheath, and much larger particles can be retained.…”

“…The RF capacitive discharge consists of two near-electrode sheaths (in which the positive space charge predominates), as well as a quasi-neutral plasma in between them (Figure 1). 32,33 A quartz optical fiber was connected to the optical spectrometer. The end of the fiber was placed vertically on the top of the tube near the boundary of the near-electrode sheath collecting optical radiation from the upper part of the discharge tube (see Figure 1).…”

Study of the Neon Dielectric Barrier Discharge on a Capacitively Coupled Radio Frequency at a Low Pressure with Metastable Atom Density: Effect of the Pressure

“…In the cathode phase, the electrons are swept out of the layer back into plasma. As a result, they acquire the energy with the appearance of peaks on the electron temperature plot near the boundaries of the layers [37][38]. On the contrary, the cooling phenomenon created by means of the electron density and the ground state of neon atoms, as well as the threshold ionization and excitation are weakening in the sheath thickness.…”