Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : April 22, 2024 - April 23, 2024
Plasma CVD requires the generation of high-density plasma when depositing films on the internal surface of millimeter-size tubes. Hollow cathode discharge (HCD) is one of the plasma generation methods to obtain such high-density plasma in tubes. We have been investigating the difference in the deposition results between impulse and non-impulse discharges in DLC (diamond-like carbon) coating onto the inner surface of a small hole using plasma generation by HCD. The results so far have shown that many arc marks were observed on the DLC film formed by impulse discharge. In this study, we verified whether the arc marks continuously increase as the current increases from the initial stage of the transition from impulse discharge to non-impulse discharge. First, a DLC film was deposited on the inner surface of a small hole (4.4 mm inner diameter and 50 mm length) under conditions of non-impulse discharge with a discharge ON time of 0.09 ms. Next, we confirmed that by slightly increasing the discharge ON time to 0.1 ms, the discharge transitioned to an impulse discharge with a maximum current exceeding 40 A, and under these discharge conditions we similarly deposited a DLC film on the inner surface of the small hole. Comparing the two film formation results, many arc marks were seen in the impulse discharge. It was suggested that during the transition from non-impulse discharge to impulse discharge, arcs begin to occur from the initial stage of the transition, and the number of arc marks increases continuously as the current increases.
