大型ヘリカル装置(LHD)用ガスパフ装置

Abstract

The method to increase the purity of fuel gases used for the gas puff device and the characteristics of the piezovalve used for the control of injection of fuel gases in the Large Helical Device (LHD) were reported. Ultra high purity gases were used as the fuel gases and EP (Electrolytic Polishing) pipes or CRP (Cr2O3 Passivation) pipes were used for gas supply lines. The line from the gas tank to the purifier was purged with gas. A 90A exhaust valve was attached along with the line from the purifier to the piezovalve and the line was purged with gas. Three kinds of valves of 100, 50, and 5 Pa cu m/s were used as high speed piezovalves. The purity test of the fuel gas reached approximately the goal. At the performance tests of the piezovalve, the flux was close to the specification at first, but it decreased with repeated use.

大型ヘリカル装置(LHD)に用いられるガスパフ装置の燃料ガスの純度向上方法や、燃料ガスの注入制御に用いたピエゾバルブの特性を中心に述べた。燃料ガスには超高純度ガスを使用し、ガス供給配管にはEP(電解研磨)管またはCRP(Cr2O3不動態処理)管を用いた。ガスボンベから精製装置まではガス置換を行った。精製装置からピエゾバルブまでは90Aの排気配管を沿わせ、真空排気とガス置換を行った。高速ピエゾバルブには100、50、および5Pa立方メートル/sの3種類を用いた。燃料ガスの純度試験では、目標にかなり近づいた。ピエゾバルブの性能試験では、初期のころは仕様に近い流量であったが、使用を繰り返すうちに流量が減少していった。