Recent progress on high performance steady state plasmas in the superconducting tokamak TRIAM-1M

Itoh, Susumu; Sato, K. N.; Nakamura, K.; Zushi, H.; Sakamoto, M.; Hanada, K.; Jotaki, E.; Makino, Kazutaka; Shoji, K.; Nakashima, Hideharu; Yoshida, Naoki

doi:10.1088/0029-5515/39/9y/304

Cited by 44 publications

(41 citation statements)

References 36 publications

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“…Combined with the properties of high melting point and low sputtering yield, Mo and W are suitable to be used as plasma facing materials in fusion and fission reactors. Actually, Mo has been used in many current tokamaks (such as TRIAM-1M and FTU) and fusion studies, [64][65][66] and W has been chosen as plasma facing materials (PFMs) in ITER. 67 However, a vacancy in Mo and W could trap more H atoms (12 H atoms) than the other metals.…”

Section: Issues and Challengementioning

confidence: 99%

Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

You¹,

Kong²,

Wu³

et al. 2013

AIP Advances

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First-principles calculations are performed to investigate the dissolving, trapping and detrapping of H in six bcc (V, Nb, Ta, Cr, Mo, W) and six fcc (Ni, Pd, Pt, Cu, Ag, Au) metals. We find that the zero-point vibrations do not change the site-preference order of H at interstitial sites in these metals except Pt. One vacancy could trap a maximum of 4 H atoms in Au and Pt, 6 H atoms in V, Nb, Ta, Cr, Ni, Pd, Cu and Ag, and 12 H atoms in Mo and W. The zero-point vibrations never change the maximum number of H atoms trapped in a single vacancy in these metals. By calculating the formation energy of vacancy-H (Vac-Hn) complex, the superabundant vacancy in V, Nb, Ta, Pd and Ni is demonstrated to be much more easily formed than in the other metals, which has been found in many metals including Pd, Ni and Nb experimentally. Besides, we find that it is most energetically favorable to form Vac-H1 complex in Pt, Cu, Ag and Au, Vac-H4 in Cr, Mo and W, and Vac-H6 in V, Nb, Ta, Pd and Ni. At last, we examine the detrapping behaviors of H atoms in a single vacancy and find that with the heating rate of 10 K/min a vacancy could accommodate 4, 5 and 6 H atoms in Cr, Mo and W at room temperature, respectively. The detrapping temperatures of all H atoms in a single vacancy in V, Nb, Ta, Ni, Pd, Cu and Ag are below room temperature

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Section: Issues and Challengementioning

confidence: 99%

Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

You¹,

Kong²,

Wu³

et al. 2013

AIP Advances

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“…We have examined a variety of radio frequency CD options including LH waves, EC waves and high harmonic fast waves (HHFW). Of these, lower hybrid waves have been studied most extensively, with a large experimental data base [20] that includes demonstation of off-axis drive to reach a reverse-shear configuration on Tore Supra and sustainment of hour-long discharges on TRIAM-1M [21]. In reactorgrade plasmas, the wave typically propagates into the plasma and becomes totally damped before reaching the plasma core.…”

Section: Lower Hybrid System For Off-axis CDmentioning

confidence: 99%

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Jardin

Kessel

Mau

et al. 2006

Fusion Engineering and Design

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The advanced tokamak is considered as the basis for a fusion power plant. The ARIES-AT design has an aspect ratio of A ≡ R/a = 4.0, an elongation and triangularity of κ = 2.17, δ = 0.84 (evaluated at the separatrix surface), a toroidal beta of β = 9.2% (normalized to the vacuum toroidal field on at the plasma center), which corresponds to a normalized beta of β N ≡ 100 × β/(I P (M A)/a(m)B(T )) = 5.4. These beta values are chosen to be 10% below the ideal MHD stability limit. The bootstrap-current fraction is f BS ≡ I BS /I P = 0.91. This leads to a design with total plasma current I P = 12.8M A, and toroidal field of 11.1T (at the coil edge) and 5.8T (at the plasma center). The major and minor radii are 5.2 and 1.3 m. The effects of H-mode edge gradients and the stability of this configuration to non-ideal modes is analyzed. The current drive system consists of ICRF/FW for on-axis current drive and a Lower Hybrid system for off-axis. Transport projections are presented using the GLF23 model. The approach to power and particle exhaust using both plasma core and scrape-off-layer radiation is presented.

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“…Alcator C-Mod, along with several limiter tokamaks ͓Frascati Tokamak Upgrade ͑FTU͒ and Tokamak Research Institute for Applied Mechanics ͑TRIAM͔͒, have molybdenum PFCs. [9][10][11] Molybdenum is similar to tungsten in that it has a high temperature limit and low tritium retention. 12 Other tokamak programs have been experimenting with tungsten PFCs, 13 most notably ASDEX-Upgrade where the carbon PFC tiles are gradually being replaced with tungsten-coated carbon tiles.…”

Section: Introductionmentioning

confidence: 99%

Operation of Alcator C-Mod with high-Z plasma facing components and implications

et al. 2006

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Studies of potential plasma facing component ͑PFC͒ materials for a magnetic fusion reactor generally conclude that tungsten is the best choice due to its low tritium ͑T͒ retention, capability to handle high heat fluxes with low erosion, and robustness to nuclear damage and activation. ITER ͓F. Perkins et al., Nucl. Fusion 39, 2137 ͑1999͔͒ may operate with all tungsten PFCs to provide the necessary operational experience for a reactor. Alcator C-Mod ͓I. Hutchinson et al., Phys. Plasmas 1, 1511 ͑1994͔͒ operates with molybdenum ͑Mo͒ high-Z PFCs, which have very similar properties to tungsten. The experiments described herein have provided a unique comparison of operation with or without in situ boron coatings applied to the molybdenum PFCs; the latter are likely most relevant to ITER and beyond. ICRF-heated H-modes were readily achieved without boron coatings although the resultant enhancement in energy confinement was typically small ͑H ITER,89 ϳ 1͒. Molybdenum concentrations, n Mo / n e , rise rapidly after the H-mode transition up to 0.1%, cooling the plasma by line radiation, reducing energy confinement, and/or causing a back H / L transition. Surprisingly, the primarily molybdenum PFC surfaces retain 3.5− 5.0ϫ 10 20 of injected D 2 molecules per discharge, corresponding to 50% of the injected gas. Plasma current disruptions, both randomly occurring over the course of a day, or planned, reduce the retained D long term. After applying boron coatings, n Mo / n e was reduced by a factor of 10-20 with H ITER,89 approaching 2. A world-record volume-average plasma pressure of 1.8 atm at 5.4 T was achieved at the ITER normalized ␤. The effects of each boronization are found to be limited in time, correlated to time-integrated input energy. Intra-and inter-discharge boronization techniques have been developed with the latter being the most successful. This initial study indicates that a low-Z coating over at least a fraction of the Mo PFCs in C-Mod is needed to reduce core molybdenum levels and achieve the best energy confinement. This, together with the larger than expected D retention, raises concerns for the performance of uncoated tungsten surfaces in ITER and beyond.

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Recent progress on high performance steady state plasmas in the superconducting tokamak TRIAM-1M

Cited by 44 publications

References 36 publications

Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals

Physics basis for the advanced tokamak fusion power plant, ARIES-AT

Operation of Alcator C-Mod with high-Z plasma facing components and implications

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