Parameters of a positive column in a gliding glow discharge in air

Abstract

This paper describes the results of investigation of the positive column in a glow discharge at atmospheric pressure. The total discharge current is varied from 0.02 A to 0.22 A that corresponds to the current density from 25 A/cm2 to 125 A/cm2. It is demonstrated that the effective gas pressure in the column lies in a range (60–90) Torr, and the reduced electric field is changed from 16 V/cm Torr at minimum current to 8 V/cm Torr when the current is increased to 0.22 A. The principal processes that are responsible for sustaining the plasma column have been defined. The main channel of the charged particle losses is the dissociative recombination of the ion NO+. The comparable contribution into the ionization gives the ionizing collisions of electrons with the oxygen molecules in the ground state, the ionization of NO molecules, and the associative ionisation when the metastable nitrogen molecules collide with each other.

Nonsteady-state processes in a low-current discharge in airflow and formation of a plasma jet

“…The plasma column moves along the coaxial part of the electrodes. The column displacement here and the discharge properties resemble that for the gliding arc or gliding glow discharge [9,42,[48][49][50]. After a time interval of 4.6 ms, the discharge burning voltage begins to increase smoothly.…”

“…Let us consider, for example, the instant of time just before t 1 when the column length is maximal. The discharge burning voltage here V d ≈1500 V, the current i=0.08 A and the voltage at the positive column V pc =1200 V. For such a current the electric field in the column E pc =910 V cm −1 [9], and we obtain that the column length l pc =1.3 cm that is the column is attached to the end of the section 2. At the instant just after t 1 (that is just after the repeated breakdown) we have V d ≈750 V, i=0.14 A and V pc =450 V. For the current i=0.14 A, the electric field in the column E pc =700 V cm −1 so that the column length l pc =0.64 cm.…”

“…It is seen that the anode spot moves over the section 2. As district to the cathode current attachment in the gliding glow discharge that moves over surface smoothly [9,42], the anode spot displaces in a jump (stick-slip) manner. This means that the anode spot disappears in a previous place of attachment and originates in a new place down the gas flow.…”

“…Hence, we have an information on the length of plasma column during its displacement. However, even if the direct observation of the discharge with temporal resolution is not provided, we are able to estimate the length of plasma column based on the results of paper [9]. In this paper, the careful study of the constricted plasma column in the gliding glow discharge has been carried out.…”

“…In recent years, considerable interest has been attracted to the investigations of the low-current atmosphericpressure discharges in gas flow [1][2][3][4][5]. A variety of the discharge types and the electrode configurations are used in the experiments [2,3,[6][7][8][9][10][11][12][13][14][15][16]. The present paper deals with the glow-type discharge in airflow in the electrode system of the classical coaxial plasmatron [3,[17][18][19][20][21][22].…”