CPC F04B 53/14 (2013.01) [F04B 15/00 (2013.01); F16J 1/006 (2013.01); G01N 30/32 (2013.01); G01N 2030/326 (2013.01)] | 10 Claims |
1. A plunger comprising:
a plunger main body section made of sapphire, having a pillar shape, and comprising a fitting hole that is non-penetrating and that extends in a central axis direction from one end portion of the plunger main body section;
a core portion inserted into the fitting hole and having a higher thermal conductivity than the sapphire; and
a joint layer interposed between
an inner peripheral surface and a bottom surface of the fitting bole of the plunger main body section and
an outer peripheral surface and a tip surface of the core portion, the joint layer being configured to bond the plunger main body section and the core portion.
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