Properties of nitrogen-implanted beryllium and its interaction with energetic deuterium

Oberkofler, M.; Linsmeier, Ch.

doi:10.1088/0029-5515/50/12/125001

Cited by 23 publications

(18 citation statements)

References 38 publications

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“…This dynamics can be ascribed to the formation of beryllium nitride within the ion penetration range as it has been observed in recent studies [8]. Impinging nitrogen projectiles are implanted at their ion penetration depth.…”

Section: Resultssupporting

confidence: 57%

“…Impinging nitrogen projectiles are implanted at their ion penetration depth. It was observed [8] that the thickness of the beryllium nitride layer, which builds, when a beryllium surface is bombarded with energetic nitrogen atoms, is of the order of the ion penetration depth in the surface. From this it can be inferred that generally the majority of projectiles will remain at the depth at which they come to rest in the surface and do not diffuse much beyond the implantation zone into the underlying beryllium bulk.…”

Section: Resultsmentioning

confidence: 99%

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Interaction of nitrogen ions with beryllium surfaces

Dobes

Köppen

Oberkofler

et al. 2014

Nuclear Instruments and Methods in Physics Research Section B:

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The interaction of energetic nitrogen projectiles with a beryllium surface is studied using a highly sensitive quartz crystal microbalance technique. The overall mass change rate of the beryllium sample under N2 + ion impact at an ion energy of 5000 eV (i.e. 2500 eV per N) is investigated in situ and in real--time. A strong dependency of the observed mass change rate on the nitrogen fluence (at constant flux) is found and can be attributed to the formation of a nitrogen containing mixed material layer within the ion penetration depth. The presented data elucidate the dynamics of the interaction process and the surface saturation with increasing nitrogen fluence in a unique way. Basically, three distinct interaction regimes can be discriminated, which can be linked to the evolution of the surface composition upon nitrogen impact.Steady state surface conditions are obtained at a total cumulative nitrogen fluence of ~8.3·10 17 N atoms per cm 2 . In dynamic equilibrium, the interaction is marked by continuous surface erosion. In this case, the observed total sputtering yield becomes independent from the applied nitrogen fluence and is of the order of 0.4 beryllium atoms per impinging nitrogen atom.

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Section: Resultssupporting

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Interaction of nitrogen ions with beryllium surfaces

Dobes

Köppen

Oberkofler

et al. 2014

Nuclear Instruments and Methods in Physics Research Section B:

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“…It is known that metal surfaces can act as efficient catalysts for the formation of ammonia from hydrogen and nitrogen (13; 14). In the here 6 presented experiments any ammonia produced will not appear in the gas balance since at liquid nitrogen temperatures it has a vapor pressure of 10 -11 mbar. It is, therefore, pumped by the liquid nitrogen cryo panel and cannot be recovered upon regeneration of only the LHe panel.…”

Section: Gas Balancementioning

confidence: 94%

First nitrogen-seeding experiments in JET with the ITER-like Wall

Oberkofler¹,

Douai²,

Brezinsek³

et al. 2013

Journal of Nuclear Materials

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In this contribution we present results from the first N 2 seeding experiments in JET performed after installation of the ITER-like Wall. Gas balance measurements for seeded L-mode 2 possible influence of ammonia production on this apparent retention is discussed. Plasma parameters and impurity content were monitored throughout the seeded discharges as well as during subsequent clean-up discharges. These experiments give first insight into phenomena related to the use of nitrogen as seeding gas in JET with the ITER-like Wall, such as ammonia production and nitrogen legacy.

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“…In a recent study of bombarding Be with energetic deuterium and nitrogen ions, the formation of mixed Be x N y compounds was observed [5]. These compounds were thermally stable and showed no nitrogen release up to 1000K.…”

Section: Introductionmentioning

confidence: 99%

Interaction of high flux deuterium/nitrogen plasmas with beryllium

et al. 2011

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Before nitrogen can be used as radiator for edge plasma temperature control in experiments with beryllium as the wall material, the compatibility of nitrogen containing plasma with beryllium has to be tested. Therefore beryllium samples were exposed to a variety of mixed N2/D2 plasmas in PISCES-B and codeposits from the sputtered material were collected. It was found that introducing N2 to a D2-plasma reduces Be erosion signicantly but recovery to the pre-N2 levels is possible in pure D2 plasma. Berylliated vessel walls can be a reservoir for N2 and chemical processes probably play a signicant role during nitriding and N2 removal. Nitrided target samples remain conductive and did not lead to additional arcing but codeposits are insulating. Thermal desorption measurements of nitrided and un-nitrided target samples were comparable, while codeposits show a slightly reduced D retention. However D release for both target and codeposits is shifted ≈ 100 K to higher temperatures, above 510 K.

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Properties of nitrogen-implanted beryllium and its interaction with energetic deuterium

Abstract: Abstract.Recent successful experiments with nitrogen as a seeding gas in fusion plasma PACS numbers: 28.52. Fa,79.20.Rf,82.65.+r,82.80.Pv,82.80.Yc Properties of nitrogen-implanted beryllium and its interaction with energetic deuterium3

Cited by 23 publications

References 38 publications

Interaction of nitrogen ions with beryllium surfaces

Interaction of nitrogen ions with beryllium surfaces

First nitrogen-seeding experiments in JET with the ITER-like Wall

Interaction of high flux deuterium/nitrogen plasmas with beryllium

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