Feedback control of radiation region in radiative divertor plasma on JT-60U tokamak

Tamai, Hiroshi; Konoshima, S.; Hosogane, N.; Asakura, N.; Sakata, Shinya; Saito, Nobuo; Akiba, K.; Akasaka, H.; Kawamata, Y.; Kurihara, Kenichi

doi:10.1016/s0920-3796(97)00175-0

Cited by 12 publications

(10 citation statements)

References 7 publications

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“…Hence, the D retention on the bottom of the outer dome wing tile could not be originated from high-energy deuterium implantation. That is also not likely due to low-energy deuterium flux, because neutral pressure at the inner divertor region was higher than that at the outer divertor region in typical operation of JT-60U [21]. In contrast, the D/C ratio in the outer dome wing tile was higher than that of the inner dome wing as shown in Fig.…”

Section: Deuterium and Hydrogen Retention In The Divertor Surfacementioning

confidence: 88%

Retention characteristics of hydrogen isotopes in JT-60U

Masaki¹,

Sugiyama

Hayashi³

et al. 2005

Journal of Nuclear Materials

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Section: Deuterium and Hydrogen Retention In The Divertor Surfacementioning

confidence: 88%

Retention characteristics of hydrogen isotopes in JT-60U

Masaki¹,

Sugiyama

Hayashi³

et al. 2005

Journal of Nuclear Materials

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“…→ gas injection (div.) JT-60U [86] In-divertor radiation Bolometer (core) → gas injection (div.) DIII-D [82] Wall and limiter temperature IR camera set → plasma control system, also protection interlock Tore-Supra (planned) [ nition capability with a control algorithm selection capability so as to make the algorithm selection state dependent.…”

Section: The Intent Of Thementioning

confidence: 99%

Chapter 8: Plasma operation and control

MHD¹,

Drive²,

Diagnostics³

et al. 1999

Nucl. Fusion

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Wall conditioning of fusion devices involves removal of desorbable hydrogen isotopes and impurities from interior device surfaces to permit reliable plasma operation. Techniques used in present devices include baking, metal film gettering, deposition of thin films of low-Z material, pulse discharge cleaning, glow discharge cleaning, radio frequency discharge cleaning, and in situ limiter and divertor pumping. Although wall conditioning techniques have become increasingly sophisticated, a reactor scale facility will involve significant new challenges, including the development of techniques applicable in the presence of a magnetic field and of methods for efficient removal of tritium incorporated into co-deposited layers on plasma facing components and their support structures. The current status of various approaches is reviewed, and the implications for reactor scale devices are summarized. Creation and magnetic control of shaped and vertically unstable elongated plasmas have been mastered in many present tokamaks. The physics of equilibrium control for reactor scale plasmas will rely on the same principles, but will face additional challenges, exemplified by the ITER/FDR design. The absolute positioning of outermost flux surface and divertor strike points will have to be precise and reliable in view of the high heat fluxes at the separatrix. Long pulses will require minimal control actions, to reduce accumulation of AC losses in superconducting PF and TF coils. To this end, more complex feedback controllers are envisaged, and the experimental validation of the plasma equilibrium response models on which such controllers are designed is encouraging. Present simulation codes provide an adequate platform on which equilibrium response techniques can be validated. Burning plasmas require kinetic control in addition to traditional magnetic shape and position control. Kinetic control refers to measures controlling density, rotation and temperature in the plasma core as well as in plasma periphery and divertor. The planned diagnostics (Chapter 7) serve as sensors for kinetic control, while gas and pellet fuelling, auxiliary power and angular momentum input, impurity injection, and non-inductive current drive constitute the control actuators. For example, in an ignited plasma, core density controls fusion power output. Kinetic control algorithms vary according to the plasma state, e.g. H-or L-mode. Generally, present facilities have demonstrated the kinetic control methods required for a reactor scale device. Plasma initiation -breakdown, burnthrough and initial current ramp -in reactor scale tokamaks will not involve physics differing from that found in present day devices. For ITER, the induced electric field in the chamber will be ∼0.3 V• m −1 -comparable to that required by breakdown theory but somewhat smaller than in present devices. Thus, a start-up 3 MW electron cyclotron heating system will be employed to assure burnthrough. Simulations show that plasma current ramp up and termination in a reactor scale device ...

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“…The DM4 sample had maximum D/ 12 C of 0.053 at 1.6 lm depth. In typical plasma operations of JT-60U, the neutral pressure at the outer divertor region was smaller than that at the inner divertor region [17]. However, NRA results showed the deuterium concentration in the outer dome wing tile (DM3 and DM4) was higher than that of the inner dome wing (DM1).…”

Section: Deuterium Accumulation In the Dome Regionmentioning

confidence: 91%