| 摘要 |
PURPOSE:To enable abnormal discharge to be grasped automatically and quantitatively, by memorizing/computing data on changes in amplitude of electrode voltage. CONSTITUTION:High frequency power is applied to a point A of an upper electrode 104a in a plasma processor 1. When abnormal discharge occurs, a detector 2 detects this abnormal voltage on the point A and gives a signal B to a differentiator 3. The differentiator 3 picks up points of changes in the signal B, that is, a start point and a finish point in the abnormal discharge, and it outputs a signal C. A memory and computing means 8 discriminates species of the abnormal discharge in accordance with respective data obtained by a signal processing means and it stores four data of hour, time, peak voltage, and species, and these data are displayed on a display means 9, as needed. When excessively abnormal voltage occurs, an alarm is raised by an alarming means 10.
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