Studies of the outer-off-midplane lower hybrid wave launch scenario for plasma start-up on the TST-2 spherical tokamak

N. Tsujii, A. Ejiri, Y. Ko, Y. Peng, K. Iwasaki, Y. Lin, K. Shinohara, O. Watanabe, S. Jang, T. Hidano2024年8月Nuclear FusionIF 3 出版社

Establishment of an efficient central solenoid (CS) free tokamak plasma start-up method may lead to an economical fusion reactor. CS-free start-up using lower hybrid (LH) waves has been studied on the TST-2 spherical tokamak. Plasma current of about a quarter of CS-driven discharges has been obtained fully non-inductively using the outer-midplane and top LH launchers. Recently, an outer-off-midplane LH launcher was developed to achieve higher plasma current by optimizing for core absorption and minimal fast electron losses. Using the (outer-)off-midplane launcher, fully non-inductive plasma current start-up up to about 8 kA was achieved. Coupled ray-tracing and Fokker–Planck simulation was performed on equilibria reconstructed with an extended MHD model. It was found that the experimentally observed plasma current was in reasonable agreement with the numerical simulation. The simulation predicted appreciable orbit losses for the off-midplane launcher driven discharge at the present parameters, which was consistent with the experimentally observed x-ray radiation characteristics. The simulation showed that the current density was saturated for the present off-midplane launcher discharges and higher density and higher LH power was necessary to achieve higher plasma current.

AIによる論文要約

ENThis paper should be read by fusion researchers and engineers interested in developing efficient and cost-effective methods for starting up fusion reactors, as well as those studying the physics of lower hybrid waves and their interaction with plasma.#FusionStartup #LowerHybridWaves #SphericalTokamak #NonInductivePlasmaStart

This paper explores a new method to start up a fusion reactor without a central solenoid, using lower hybrid waves launched from an outer-off-midplane position. The researchers achieved significant non-inductive plasma current, and used simulations to understand the physics behind the experimental results.

TST-2球状トカマクにおける外部オフ中心面下部ハイブリッド波立ち上げシナリオの研究

JAこの論文は、核融合プラズマの立ち上げ手法に関心のある研究者や学生に役立つと考えられます。中心ソレノイドを必要としない経済的な核融合炉の実現に向けた取り組みに興味のある人にも参考になるでしょう。#プラズマ立ち上げ #下部ハイブリッド波 #球状トカマク #経済的核融合炉

この論文は、中心ソレノイドを必要としない経済的な核融合炉の実現に向けて、TST-2球状トカマクにおける下部ハイブリッド波を用いたプラズマ立ち上げ手法について報告しています。外部オフ中心面の下部ハイブリッド波ランチャーを用いることで、完全非誘導的に8kAまでのプラズマ電流を立ち上げることに成功しました。シミュレーションの結果、現在のパラメータでは高速電子の軌道損失が大きいことが分かり、さらなる高密度化と高出力化が必要であることが示唆されています。