CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

Westerhout, J.; Cardozo, N.J. Lopes; Rapp, J.; Rooij, G.J. van

doi:10.1063/1.3238295

Cited by 25 publications

(29 citation statements)

References 14 publications

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“…A similar trend has been observed for various grades of carbon materials (CFC, graphite) and is further discussed in [10]. It should be noted that the inverse photon efficiency for CH has been found to be constant in the range of electron temperatures investigated here [12]. The NCD and MCD coatings show a reduced chemical erosion compared to graphite by a factor of about 2, at least for electron temperatures below 1 eV.…”

Section: Erosion Of Diamondsupporting

confidence: 84%

Interactions of diamond surfaces with fusion relevant plasmas

et al. 2009

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The outstanding thermal properties of diamond and its low reactivity towards hydrogen may make it an attractive plasma-facing material for fusion and calls for a proper evaluation of its behaviour under exposure to fusion-relevant plasma conditions. Micro and nanocrystalline diamond layers, deposited on Mo and Si substrates by hot filament chemical vapour deposition (CVD), have been exposed both in tokamaks and in linear plasma devices to measure the erosion rate of diamond and study the modification of the surface properties induced by particle bombardment. Experiments in Pilot-PSI and PISCES-B have shown that the sputtering yield of diamond (both physical and chemical) was a factor of 2 lower than that of graphite. Exposure to detached plasma conditions in the DIII-D tokamak have evidenced a strong resistance of diamond against erosion under those conditions.

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Section: Erosion Of Diamondsupporting

confidence: 84%

Interactions of diamond surfaces with fusion relevant plasmas

et al. 2009

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“…Figure 6 shows that i) Gerö band D/XB values are fairly robust quantities (no significant change when replacing the 1987 hydrocarbon database [25] with the present one), but ii) orders of magnitude higher Gerö band emission rates at low temperatures than hitherto expected. If one makes the realistic assumption that 5-20% of all theoretically permitted DR channels of Table 14 lead to the CD(A) state, the experimental values for D/XB (∼ 50 − 100, independent of Te below 2 eV) found at the linear plasma device PILOT-PSI [33] would be confirmed. The future challenge to render Gerö band plasma diagnostic reliable at these ITER divertor relevant temperatures hence is to establish "collisional radiative" equilibrium models for the CD molecule with coupling to larger molecules and direct population of CD * states via DR channels.…”

Section: Dissociative Recombination (Dr)mentioning

confidence: 85%

Hydrocarbon Collision Cross Sections for Magnetic Fusion: The Methane, Ethane and Propane Families

Reiter

Janev

2010

Contrib. Plasma Phys.

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Kinetic analysis of the behaviour of hydrocarbons in fusion plasmas requires knowledge of cross sections for their most relevant collision processes. Upgrades and extensions of the commonly used HYDKIN (HYDride KINetics) online cross section database (based on compilations in 2002) and its data analysis toolbox for collisions of hydrocarbons with electrons and protons in relevant fusion plasma conditions are presented. Newly identified channels for dissociative recombination provide strongly reduced D/XB ratios for Gerö-Band spectroscopy at low temperatures compared to earlier results, in accordance with experimental findings.

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“…Earlier, we have reported formation of large cauliflower-like particles on the sample areas exposed to the highest particle flux. [12][13][14] In this article, we present results of detailed analyses of the formed particles, list possible growth mechanisms, and propose an explanation of their presence in the highest flux region. The Pilot-PSI linear plasma generator is described in detail in Ref.…”

Section: à3mentioning

confidence: 99%

“…30 Here, the CH A-X band emission was recorded by a dedicated spectrometer (wavelength range: 420-438 nm, spectral resolution of $0:1 nm at FWHM). 19,31 Inverse photon efficiency ðPEÞ À1 was used to convert the CH photon flux / CH into the methane particle flux C CH 4 [see Eq. (2)].…”

Section: B Chemical Sputtering Measurements In Pilot-psimentioning

confidence: 99%

Reorganization of graphite surfaces into carbon micro- and nanoparticles under high flux hydrogen plasma bombardment

Bystrov

Vegt

Temmerman

et al. 2012

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Fine-grain graphite samples were exposed to high density low temperature (ne∼1020 m−3, Te∼1 eV) hydrogen plasmas in the Pilot-PSI linear plasma generator. Redeposition of eroded carbon is so strong that no external precursor gas injection is necessary for deposits to form on the exposed surface during the bombardment. In fact, up to 90% of carbon is redeposited, most noticeably in the region of the highest particle flux. The redeposits appear in the form of carbon microparticles of various sizes and structures. Discharge parameters influence the efficiency of the redeposition processes and the particle growth rate. Under favorable conditions, the growth rate reaches 0.15 μm/s. The authors used high resolution scanning electron microscopy and transmission electron microscopy to study the particle growth mode. The columnar structure of some of the large particles points toward surface growth, while observation of the spherical carbon nanoparticles indicates growth in the plasma phase. Multiple nanoparticles can agglomerate and form bigger particles. The spherical shape of the agglomerates suggests that nanoparticles coalesce in the gas phase. The erosion and redeposition patterns on the samples are likely determined by the gradients in plasma flux density and surface temperature across the surface.

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CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

Cited by 25 publications

References 14 publications

Interactions of diamond surfaces with fusion relevant plasmas

Interactions of diamond surfaces with fusion relevant plasmas

Hydrocarbon Collision Cross Sections for Magnetic Fusion: The Methane, Ethane and Propane Families

Reorganization of graphite surfaces into carbon micro- and nanoparticles under high flux hydrogen plasma bombardment

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