Spontaneous Formation of Closed-Field Torus Equilibrium via Current Jump Observed in an Electron-Cyclotron-Heated Plasma

Yoshinaga, T.; Uchida, Masaki; Tanaka, Hitoshi; Maekawa, Takashi

doi:10.1103/physrevlett.96.125005

Cited by 60 publications

(88 citation statements)

References 12 publications

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“…125 After closed flux surfaces are formed, pressure-driven "bootstrap" currents can be generated within the flux surfaces to maintain the plasma current. 126 The ECH/EBW start-up experiments have been performed in a number of ST devices in recent years: LATE, 26,127 TST-2, 128,129 CPD, 130 QUEST, 131 and MAST. 132 An illustrative ECH/EBW start-up and ramp-up experiment was performed on the LATE device, which is shown in Fig.…”

Section: Solenoid-free Start-up a Motivation For St Researchmentioning

confidence: 99%

Recent progress on spherical torus research

Ono

Kaita

2015

Physics of Plasmas

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The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ∼ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ∼ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of an attractive fusion energy power source. Since the start of the two mega-ampere class ST facilities in 2000, the National Spherical Torus Experiment in the United States and Mega Ampere Spherical Tokamak in UK, active ST research has been conducted worldwide. More than 16 ST research facilities operating during this period have achieved remarkable advances in all fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

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Section: Solenoid-free Start-up a Motivation For St Researchmentioning

confidence: 99%

Recent progress on spherical torus research

Ono

Kaita

2015

Physics of Plasmas

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“…7, which is very long time compared with that determined by atomic processes such as ionization. One of the possible explanations for a slow density change in time is that better confinement region appeared at the low field side due to bootstrap current [6].…”

Section: High Density Plasma Generation By High Power Rf Sourcementioning

confidence: 98%

High density plasma generation by RF ohmic discharge in toroidal divertor simulator NAGDIS-T

Nagase

Masuda

Ohno

et al. 2007

Journal of Nuclear Materials

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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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Spontaneous Formation of Closed-Field Torus Equilibrium via Current Jump Observed in an Electron-Cyclotron-Heated Plasma

Cited by 60 publications

References 12 publications

Recent progress on spherical torus research

Recent progress on spherical torus research

High density plasma generation by RF ohmic discharge in toroidal divertor simulator NAGDIS-T

The Physics of Tokamak Start-up

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