Electron-capture cross sections for low-energy highly charged neon and argon ions from molecular and atomic hydrogen

Can, C.; Gray, Tom J.; Varghese, Shinto; Hall, James M.; Tunnell, L. N.

doi:10.1103/physreva.31.72

Cited by 30 publications

(10 citation statements)

References 28 publications

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“…The scaling relations apply also for ions in charge states q = 3 and 4 except for reduced energies E/q 1/2 below 100 eV amu −1 . We have compared for both Ne and Ar the cross sections predicted by the scaling formulae with experimental data found in [21][22][23]. The conclusion is that, starting from q = 3, in the range of energies of the order of 100 eV amu −1 the scaled cross sections overestimate the available data for low-charge ions by a factor of 2-3 (up to q = 7 for Ne and q = 10 for Ar [22]).…”

Section: Impurity Modellingmentioning

confidence: 91%

“…We have compared for both Ne and Ar the cross sections predicted by the scaling formulae with experimental data found in [21][22][23]. The conclusion is that, starting from q = 3, in the range of energies of the order of 100 eV amu −1 the scaled cross sections overestimate the available data for low-charge ions by a factor of 2-3 (up to q = 7 for Ne and q = 10 for Ar [22]). For q = 2 the overestimation, for both Ar and Ne, is larger by more than one order of magnitude.…”

Section: Impurity Modellingmentioning

confidence: 91%

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Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Mattioli

Fournier

Puiatti

et al. 2001

Plasma Phys. Control. Fusion

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Experimental VUV spectra from the JET tokamak and from the reversed field pinch RFX have been simulated. For the former device both n = 2 to n = 2 L-shell Ar and Ne spectra (respectively, in the 14.5-43.0 and in the 35.0-80.0 nm ranges) were considered, whereas for RFX only the Ne spectrum was available. The spectra have been observed with the SPRED spectrometer. From the simulation of the spectra, relative sensitivity curves have been obtained for each instrument in the ranges of the simulation. For RFX only, it has been possible to extend this curve from ∼13.0 to ∼105 nm, by simulating intrinsic C and O emissions. The photon emission coefficients of the lines with wavelengths in the ranges of the experimental spectra were obtained from collisional-radiative models. For Ar and Ne these coefficients have been calculated by the Hebrew University Lawrence Livermore Atomic Codes atomic physics codes, whereas for C and O the corresponding coefficients have been taken from the 'Atomic Data and Analysis Structure' database. Impurity modelling is performed using a one-dimensional impurity transport code, calculating for each atomic species the radial distribution of the impurity ions. The line brightnesses are evaluated in a post-processing subroutine and the simulations of the spectra are obtained. The spectral simulations (including impurity ion transport) give confidence in the atomic physics calculations, and allow the determination of the transport coefficients in the plasma regions from which the considered ionization states emit. Finally, the obtained relative sensitivity curves of the two SPRED spectrometers have been compared with the calibrations performed by means of the branching ratio technique.

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Section: Impurity Modellingmentioning

confidence: 91%

Section: Impurity Modellingmentioning

confidence: 91%

Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Mattioli

Fournier

Puiatti

et al. 2001

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

show abstract

“…This term is included to capture the effect of the shortening of the mean free path of neutrals during the neutral diffusion processes due to ionization, dissociation, etc. The D destruction reactions included are (where 'e' in an equation refers to cold thermal electrons and 'RE' to REs) [27,[31][32][33]: goes into both direct ionization and excitation (some of which can then result in ionization through Auger processes). For high-energy electrons impacting lower charge states (0-3) of lower Z species (Ar and down), direct ionization is expected to dominate [45,46].…”

Section: Appendix a Re Plateau 1d Neutral Diffusion Modelmentioning

confidence: 99%

Study of argon assimilation into the post-disruption runaway electron plateau in DIII-D and comparison with a 1D diffusion model

et al. 2019

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The assimilation of argon injected into post-disruption runaway electron (RE) plateaus is studied and compared to the vertical loss rate for vertically unstable RE plateaus. A 1D diffusion model is developed to include neutral diffusion and ionization and is used to help in data interpretation. It is found that the radial mixing time scale of argon ions (~0.05 s) is comparable to the vertical loss timescale. Neutral argon becomes the dominant Ar species in the RE plateau for large Ar numbers (> 3 × 10 21 ); at the same time the neutral Ar diffusivity decreases due to plasma cooling, causing a saturation in the assimilation of injected Ar on the vertical loss time scale. Injection of Ar into vertically unstable RE plateaus in DIII-D does increase the vertical loss rate, as predicted by previous modeling of ITER. However, there is a decreasing trend in RE current at the wall strike as the Ar quantity is turned up or as the Ar is injected earlier, indicating a decrease in RE energy deposited to the wall.

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“…For reaction (A13), an simple average of analogous reactions involving He 2+ and Ar 2+ is used [38]. For reactions (A14)-(A18), the rate coefficients are estimated from the higher-energy measurements of [39] by extrapolating to lower energy.…”

Section: Appendix Addition Of H − Ne and H 2 To Re Plateau 1d Neutr...mentioning

confidence: 99%

Trends in runaway electron plateau partial recombination by massive H₂ or D₂ injection in DIII-D and JET and first extrapolations to ITER and SPARC

et al. 2023

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Experimental trends in thermal plasma partial recombination resulting from massive D_2 injection into high-Z (Ar) containing runaway electron (RE) plateaus in DIII-D and JET are studied for the purpose of achieving sufficiently low electron density (n_e≈10^18/m^3) to increase RE final loss MHD levels. In both DIII-D and JET, thermal electron density n_e is found to drop by ~ 100× when the thermal plasma partially recombines, with a minimum at a vacuum vessel-averaged D_2 density in the range 10^20-10^21/m^3. RE effective resistivity also drops after partial recombination, indicating expulsion of the Ar content. The n_e level after partial recombination is found to increase as RE current is increased. The amount of initial Ar in the RE plateau is not observed to have a strong effect on partial recombination. Partial recombination timescales of order 5 ms in DIII-D and 15 ms in JET are observed. These basic trends and timescales are matched with a 1D diffusion model, which is then used to extrapolate to ITER and SPARC tokamaks. It is predicted that ITER will be able to achieve sufficiently low n_e values on time scales faster than expected RE plateau vertical drift timescales (of order 100 ms), provided sufficient D_2 or H_2 is injected. In SPARC, it is predicted that achieving significant n_e recombination will be challenging, due to the very high RE current density. In both ITER and SPARC, it is predicted that achieving low n_e will be easier with Ar as a background impurity (rather than Ne).

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Electron-capture cross sections for low-energy highly charged neon and argon ions from molecular and atomic hydrogen

Cited by 30 publications

References 28 publications

Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Study of argon assimilation into the post-disruption runaway electron plateau in DIII-D and comparison with a 1D diffusion model

Trends in runaway electron plateau partial recombination by massive H₂ or D₂ injection in DIII-D and JET and first extrapolations to ITER and SPARC

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Electron-capture cross sections for low-energy highly charged neon and argon ions from molecular and atomic hydrogen

Cited by 30 publications

References 28 publications

Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Experimental and simulated VUV spectra from the JET tokamak and the reversed field pinch RFX

Study of argon assimilation into the post-disruption runaway electron plateau in DIII-D and comparison with a 1D diffusion model

Trends in runaway electron plateau partial recombination by massive H2 or D2 injection in DIII-D and JET and first extrapolations to ITER and SPARC

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Product

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About

Trends in runaway electron plateau partial recombination by massive H₂ or D₂ injection in DIII-D and JET and first extrapolations to ITER and SPARC