RF start-up and sustainment experiments on the TST-2@K spherical tokamak

Ejiri, A.; Takase, Y.; Kasahara, Hiroshi; Yamada, Teppei; Hanada, K.; Sato, K. N.; Zushi, H.; Nakamura, K.; Sakamoto, M.; Idei, H.; Hasegawa, Makoto; Iyomasa, A.; Imamura, N; Esaki, Kayoko; Kitaguchi, Masaaki; Sasaki, Kyuro; Hoshika, H.; Mitarai, O.; Nishino, Norikazu

doi:10.1088/0029-5515/46/7/003

Cited by 49 publications

(64 citation statements)

References 10 publications

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“…In fact, for ITER start-up with a multi-pole null magnetic field configuration, addition of an extra 3 MW RF power is planned along with Ohmic power to facilitate reliable breakdown over a wide range of error field and pressure conditions [3]. The possibilities of plasma current generation in RF plasma have been demonstrated in CDX-U [4] LATE [5] and TST-2@K [6] under a weak magnetic mirror configuration. Such current formation as well as ramp up under a steady B z field is considered to be responsible for the change of magnetic field topology from an open field equilibrium to a closed field equilibrium.…”

Section: Introductionmentioning

confidence: 99%

Two Dimensional Li Beam Imaging to Study the Magnetic Field Configuration Effects on Plasma Confinement in Spherical Tokamak CPD

Bhattacharyay

Zushi

Morisaki

et al. 2007

Plasma and Fusion Research

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Two dimensional lithium beam imaging technique has been applied in the spherical tokamak, CPD (Compact Plasma wall interaction experimental Device), to study the effects of various magnetic field configurations on RF plasma confinement topology. The performance of the lithium sheet beam is absolutely calibrated by a quartz crystal monitor. Experimental results show that plasma initiation takes place at the electron cyclotron resonance layer in a simple torus configuration and then it expands quickly to the low magnetic field side. Different magnetic field configurations critically affect the RF plasma confinement topology. A sharp lower boundary exists for the RF plasma in magnetic null configuration. Magnetic connection length plays the key role in defining plasma boundary and the critical value of connection length for plasma to exist in CPD is found to be ∼ 5-6 meter for a given pressure condition.

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Section: Introductionmentioning

confidence: 99%

Two Dimensional Li Beam Imaging to Study the Magnetic Field Configuration Effects on Plasma Confinement in Spherical Tokamak CPD

Bhattacharyay

Zushi

Morisaki

et al. 2007

Plasma and Fusion Research

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“…Plasma heating could be observed in the case of application to ohmic heated plasma. Full non-inductive plasma current of 4 kA for 0.3 sec could be sustained by only-RF on TST-2 [11]. First observation of plasma heating via X-B scenario was also reported from TST-2 experiments [12].…”

Section: Non-inductive Current Drive In Phase I and Iimentioning

confidence: 84%

Steady-State Operation Scenario and the First Experimental Result on QUEST

Hanada

Sato

Zushi

et al. 2010

Plasma and Fusion Research

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QUEST focuses on the steady state operation of the spherical tokamak by controlled PWI and electron Bernstein wave current drive. One of the main purposes of QUEST is an achievement of long duration discharge with MW-class injected power. As the result, QUEST should be operated in the challenging region on heat and particle handling. To do the particle handling, high temperature all metal wall up to 623 K and closed divertors are planned, which is to realize the steady-state operation under recycling ratio, R = 1. This is a dispensable check to DEMO, because wall pumping should be avoided as possible in the view of tritium retention. The QUEST project will be developed in increment step such as, I. low β steady state operation in limiter configuration, II. low β steady state operation in divertor configuration, III. relatively high β steady state operation in closed divertor configuration. Phase I in the project corresponds to these two years, and final goal of phase I is to make full current drive plasma up to 20 kA. Closed divertor will be designed and tested in the Phase II. QUEST is running from Oct., 2008 and the first results are introduced.

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“…Lower Hybrid Current Drive (LHCD) start-up to 100 kA was demonstrated on PLT 40 and ECRH was used to provide start-up to low current levels on DII-D 41 , TS2 42 and LATE 43 . For the ST, however, Electron-Bernstein Wave (EBW) seems most promising 44 .…”

Section: Start-up Using Rf Wavesmentioning

confidence: 99%

The Physics of Tokamak Start-up

Mueller¹

2012

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Tokamak start-up on present-day devices usually relies on inductively induced voltage from a central solenoid. In some cases inductive startup is assisted with auxiliary power from electron cyclotron radio frequency heating.ITER, the National Spherical Torus eXperiment Upgrade and JT60, now under construction, will make use of the understanding gained from present-day devices to ensure successful start-up. Design of a spherical tokamak (ST) with DT capability for nuclear component testing would require an alternative to a central solenoid because the small central column in an ST has insufficient space to provide shielding for the insulators in the solenoid. Alternative start-up techniques such as induction using outer poloidal field coils, electron Bernstein wave start-up, coaxial helicity injection and point source helicity injection have been used with success, but require demonstration of scaling to higher plasma current.

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RF start-up and sustainment experiments on the TST-2@K spherical tokamak

Cited by 49 publications

References 10 publications

Two Dimensional Li Beam Imaging to Study the Magnetic Field Configuration Effects on Plasma Confinement in Spherical Tokamak CPD

Two Dimensional Li Beam Imaging to Study the Magnetic Field Configuration Effects on Plasma Confinement in Spherical Tokamak CPD

Steady-State Operation Scenario and the First Experimental Result on QUEST

The Physics of Tokamak Start-up

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