Extending KSTAR operation regime for advanced operation scenario development

先進運転シナリオ開発のためのKSTAR運転領域の拡大

鈴木 隆博; Kim, J. H.*; Na, Y. S.*; 井手 俊介; Mueller, D.*; 宮田 良明; Kim, H. S.*; Hahn, S. H.*; Yoon, S. W.*; Kim, W. C.*

Suzuki, Takahiro; Kim, J. H.*; Na, Y. S.*; Ide, Shunsuke; Mueller, D.*; Miyata, Yoshiaki; Kim, H. S.*; Hahn, S. H.*; Yoon, S. W.*; Kim, W. C.*

KSTARトカマクで初となる先進運転シナリオ開発に取り組んだ。標準的なHモード運転シナリオよりも高い性能を有する先進運転シナリオは、ITER及びDEMOに直接繋がる重要な研究領域である。先進運転シナリオは低い内部インダクタンスと鋸歯状不安定性の発生しない安全係数分布が特徴であるが、従来のKSTAR運転シナリオではプラズマ電流立ち上げ中に鋸歯状不安定性が発生し、実現できずにいた。今回、プラズマ電流立ち上げ初期にプラズマ体積を拡大してダイバータ配位を形成し、その後に加熱を行いつつ電流を立ち上げる新しいKSTAR運転シナリオを確立し、鋸歯状不安定性の発生しない低内部インダクタンスのプラズマを実現した。放電番号7897では閉じ込め改善度を表面安全係数6程度で先進運転領域に届く高規格化圧力を達成した。

We have started advanced operation scenario development in KSTAR in this campaign, which opens up a new research area directly connecting to ITER and DEMO. The advanced scenario, which has higher performance than the standard H-mode, typically possesses lower internal inductance li (safety factor q above unity without sawtooth). In conventional KSTAR operation scenarios, divertor configuration with high elongation is realized after or near the end of Ip ramp-up, where sawtooth activity starts during the ramp-up before entering into the higher performance phase. Thus, we need a new KSTAR operation scenario without sawtooth during the Ip ramp-up and with lower li than unity. Our idea is to delay the inductive current penetration by simultaneous EC&NB heating application into the full-bore divertor plasma during the Ip ramp-up as early as possible. After the optimization, we have successfully established a start-up scenario without sawtooth throughout the Ip ramp-up. In a shot 7897, high reaching an advanced scenario regime has been achieved in ELM-free H-mode () at .