First wall limiter in a thermonuclear device

Purpose: To simplify the structure and improve the reliability of the first wall limiter in a thermonuclear device. Constitution: In a tile made of high melting material and having a conical bottom portion and a cooling plate having an dent complementary to the conical shape of the tile, a bottomed hole for attaching a stud is disposed at the top of the conical portion of the tile and a stud insertion hole having a circular split spring engaging groove is disposed to the concaved bottom of the cooling plate. Further, there is disposed a attaching stud comprising a tile stud made of non-magnetic metal and a cooling plate stud threadingly engaged to both ends and, further, a stud made of shape memory alloy shrinked at a predetermined temperature. The tile stud is grazed to the tile, a circular split spring insertion groove is formed to the cooling plate stud, and the cooling plate is bonded by the circular split spring. Since the tile made of high melting material with no stress concentration is disposed to the cooling plate on the heat receiving side and the contact portion is made conical, it is possible to easily dispose the tile that can endure high thermal load and improve the reliability. (Kamimura, M.)