The influence of a transverse magnetic field on an unconfined glow discharge

摘要

A3-KW unconfined glow discharge in air at pressures from 0.3 to 10 millimeters of mercury has been observed in the presence of transverse magnetic flux densities from 0 to 7,000 gausses. Effects observed as the magnetic flux density is increased include: 1. The voltages of the positive column and the anode fall space exhibit very pronounced increases, the former by a factor of at least 100 between zero magnetic field and 6,000 gausses; see Figure 6. 2. The cathode fall of potential exhibits an initial rapid decrease, then a levelling off; in combination with item 1 this results in a minimum value of total discharge potential at an intermediate magnetic flux density; see Figure 6. 3. A transverse wind, directed according to the motor rule, is generated by the positive column plasma; see Figure 4. 4. The equipotentials become skewed, passing diagonally through the discharge; see Figure 5. 5. Cathode fall space phenomena, including the negative glow and the Crookes and Faraday dark spaces, become very much compressed; see Figure 2. 6. The positive column and the anode regions become much more luminous because of their greatly increased gradients; see Figure 2. 7. The sputtering rate increases greatly. 8. Random potential fluctuations, see Figure 7, increase in amplitude, and their characteristic frequency first increases, then decreases. 9. Movement of cathode fall electrons parallel to the magnetic field produces a sharply delimited hollow shell of discharge resembling an axial extension of the cathode post; see Figure 2.