Diagnostic first mirrors for burning plasma experiments (invited)

Voitsenya, V.S.; Costley, A. E.; Bandourko, V.; Bardamid, A. F.; Bondarenko, V. N.; Hirooka, Y.; Kasai, S.; Klassen, N. V.; Konovalov, V. G.; Nagatsu, Masaaki; Nakamura, K.; Orlinskij, D.V.; Orsitto, F.; Поперенко, Л. В.; Solodovchenko, S. I.; Stan, AF; Sugie, Toshiharu; Takeuchi, Masaki; Vinnichenko, M.; Vukolov, K.Yu.; Zvonkov, S.N.

doi:10.1063/1.1310580

Cited by 118 publications

(73 citation statements)

References 20 publications

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“…Figure 4 shows deposition on stainless steel and silicon wall coupons exposed to plasma operations (2521 discharges of integrated duration 821 s) and 9 boronizations between September 2000 and August 2001. Nuclear reaction analysis was performed using the 11 B( 1 H, 4 He) 8 Be reaction with a 650 keV proton beam to measure boron; 2 H( 3 He,p) 4 He reaction with 700 keV 3 He beam to measure deuterium and Rutherford back scattering with a 1500 keV proton beam to measure carbon. The carbon, deuterium and boron areal density showed strong poloidal and toroidal variations.…”

Section: Time Resolved Deposition On Nstxmentioning

confidence: 99%

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Time resolved deposition measurements in NSTX

Skinner

Kugel

Roquemore

et al. 2005

Journal of Nuclear Materials

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Abstract:Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77 m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 µg/cm 2 of deposition, however surprisingly, 15.9 µg/cm 2 of material loss occurred at 7 discharges. The net deposited mass of 13.3 µg/cm 2 matched the mass of 13.5 µg/cm 2 measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition.

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Section: Time Resolved Deposition On Nstxmentioning

confidence: 99%

“…Deposition is a serious threat to the survival of diagnostic mirrors in long-pulse next-step devices [4]. The chemical reactions and physical process involved in the deposition of amorphous hydrogenated carbon films by hydrocarbon radicals in a tokamak are complex [5].…”

Section: Introductionmentioning

confidence: 99%

Time resolved deposition measurements in NSTX

Skinner

Kugel

Roquemore

et al. 2005

Journal of Nuclear Materials

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“…The samples were sputtered by deuterium plasma ions having a wide energy distribution. The behavior of SC mirrors was investigated in the course of long-term sputtering [3,17,18], during which the mirrors showed a considerably higher resistance to relief development under erosion than the polycrystalline mirrors did (Fig. 7).…”

Section: Single-crystalline Mirrorsmentioning

confidence: 99%

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Voitsenya¹,

Bardamid²,

Donné³

2016

PHY

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In the experimental fusion reactor ITER, the plasma-facing component of each optical and/or laser diagnostic needs to be based on reflective optics with at least one mirror (first mirror) facing the thermonuclear plasma. The different kinds of radiation emanating from the burning plasma (neutrons, neutral atoms, electromagnetic radiation) create hostile operating conditions for the first mirrors. Therefore, a special program has been set up under the ITER framework aimed at solving the first mirror problem. This paper will review the main results in this field that have been obtained in the Institute of Plasma Physics, National Science Center “Kharkov Institute of Physics and Technology” (in many cases in cooperation with groups of other countries, as indicated in corresponding parts of the manuscript) during long-term investigations directed to find a solution of this problem,i.e., to find a material and accompanying precautions in order to satisfy the requirements for first mirrors. The main efforts were devoted to finding solutions to overcome the impact of the most severe deteriorating factors resulting in degradation of the optical properties of mirrors: sputtering by charge exchange atoms and deposition of contaminants. The obtained results are focused on: the effects of long term sputtering on mirror specimens fabricated from different metals with different structures (polycrystals, single crystals, metal film on metal substrates, amorphous), the effects of contaminating film and the possible protection to avoid of its appearance, the role of chemical processes for some metal mirrors, and the choice of material of laser mirrors.

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“…However, the optical properties of mirrors will change due to erosion, deposition of contaminants and particle implantation. Mirrors in the ITER divertor will likely suffer from deposition of carbon and other impurities [14].…”

Section: Exposure Of Mirrorsmentioning

confidence: 99%

Divertor and midplane materials evaluation system in DIII-D

Wong

Rudakov

Allain

et al. 2007

Journal of Nuclear Materials

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The Divertor Materials Evaluation System (DiMES) at General Atomics has successfully advanced the understanding of plasma surface interaction phenomena involving ITERrelevant materials and it has been utilized for advanced diagnostic designs in the lower divertor of DIII-D. This paper describes a series of recent successful experiments. These include the study of carbon deposition in gaps and on metallic mirrors as a function of temperature, study of dust migration from the divertor, study of methane injection in order to benchmark chemical sputtering diagnostics, and the measurement of charge exchange neutrals with a hydrogen sensor. In concert with the modification of the lower divertor of DIII-D, the DiMES sample vertical location has been modified to match the raised divertor floor. The new Mid-plane Material Exposure Sample (MiMES) design will also be presented. MiMES will allow the study and measurement of erosion and redeposition of material at the outboard mid-plane of DIII-D, including effects from convective transport. We will continue to expose relevant materials and advanced diagnostics to different plasma configurations under various operational regimes, including material erosion and re-deposition experiments, and gaps and mirror exposures at elevated temperature.

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Diagnostic first mirrors for burning plasma experiments (invited)

Cited by 118 publications

References 20 publications

Time resolved deposition measurements in NSTX

Time resolved deposition measurements in NSTX

Experimental Simulation of the Behaviour of Diagnostic First Mirrors Fabricated of Different Metals for ITER Conditions

Divertor and midplane materials evaluation system in DIII-D

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