| 摘要 |
<p>A slug tuner (60) is equipped with: a microwave transmission path (44), at the tip end of which a planar antenna (81) is attached, and which has an outside conductor (52) and an inside conductor (53) that are coaxial; and slugs (61a, 61b) capable of moving along the inside conductor (53). The outside conductor (52) has a dual-tube construction comprising a first member (521) that forms an inner tube and a second member (522) that forms an outer tube, and when the inside conductor expands due to the heat of a plasma, a gap is formed between the tip of the first member (521) and the second member (522). The outside conductor (52) has a choke structure having a choke groove (525) that extends between the first member (521) and the second member (522) from the tip end to the base end of the outside conductor (52), with a length of lambdag/2, which places the base-end side base part of the choke groove (525) in the short-circuited state, and consequently the tip end of the outside conductor (52) is in the short-circuited state.</p> |
