DETERMINATION OF POSITIVE ANODE VOLTAGE DROP IN DC CF4 GLOW DISCHARGE USING THE MOVING ANODE METHOD

In this study, the voltage drop across the anode layer of dc glow discharge in CF4 was determined using the moving anode method at different pressures (6.65...66.5 Pa) and discharge currents (less than 80 mA). For this purpose, a set of current-voltage characteristics (CVCs) of the discharge was measured for cases where the anode glow does not appear in the studied current range (short distance between the electrodes), appears at low current and then disappears with its increase, and also when it does not disappear with increasing current (longer distances), but the positive column has not yet formed. This family of CVCs for a fixed gas pressure lies between two curves (with and without anode glow), the difference between which allows us to determine the positive anode voltage drop. It is shown that the anode drop at a fixed pressure of CF4 has a non-monotonic dependence on the magnitude of the discharge current. The magnitude of the anodic drop can be 2-3 times greater than the ionization potential of CF4 molecules due to the process of dissociative electron attachment.