| 摘要 |
This invention provides a method for accurately measuring a gap distance between two electrodes. According to the method, a plasma space is formed between the electrodes, across which a DC voltage is coupled. The plasma space has a reactive gas that emits a spectrum of spectral lines. The spectrum is monitored to determine at least one line distance between the spectral lines. Finally, the gap distance can be deduced according to the line distance and a specific rule.
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