Vibrational Population of Hydrogen Molecules Excited by an RF Discharge in an Expanding Thermal Arc Plasma as Determined by Emission Spectroscopy

Otorbaev, DK; Graaf, de Mj Mark; Sanden, van de Mcm Richard; Schram, DC Daan

doi:10.1002/ctpp.2150350303

Cited by 7 publications

(2 citation statements)

References 21 publications

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“…The principle of the method was suggested in [10] and demonstrated in [11], in both cases for the nitrogen molecule. Assuming only a significant population in ν = 0 the applicability of the method to hydrogen molecules was shown by Otorbaev et al [12]. In the present study, the diagnostic is applied to H 2 plasmas, additionally taking into account the population of H 2 (ν > 0).…”

Section: Introductionmentioning

confidence: 72%

Spectroscopic diagnostics of the vibrational population in the ground state of and molecules

Fantz¹,

Heger²

1998

Plasma Phys. Control. Fusion

116

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A diagnostic method has been evaluated for measuring the relative vibrational ground-state population of molecular hydrogen and deuterium. It is based on the analysis of the diagonal Fulcher bands (d 3 u → a 3 + g ) and the Franck-Condon principle of excitation. The validity of the underlying assumptions was verified by experiments in microwave discharges and the method is recommended for application in divertor plasmas in controlled fusion experiments. By attributing a vibrational temperature T vib to the ground-state electronic level (X 1 + g ) and assuming population via the Franck-Condon principle, the upper Fulcher state vibrational distribution can be derived theoretically with T vib as parameter. Comparison with experimentally derived upper-state population gives the corresponding T vib of the ground state. The Franck-Condon factors for the d 3 u ← X 1 + g and d 3 u → a 3 + g transitions have been calculated for both hydrogen and deuterium from molecular constants using the FCFRKR code. The method has been applied to low pressure H 2 /He and D 2 /He microwave plasmas, showing good agreement of experimentally and theoretically derived upper Fulcher state vibrational distributions. The vibrational temperatures range from 3200 K to 6800 K for H 2 and 2600 K to 4000 K for D 2 . depending on molecular density, pressure and electron temperature, but indicating nearly the same vibrational population for H 2 and D 2 for comparable plasma conditions.

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Section: Introductionmentioning

confidence: 72%

Spectroscopic diagnostics of the vibrational population in the ground state of and molecules

Fantz¹,

Heger²

1998

Plasma Phys. Control. Fusion

116

View full text Add to dashboard Cite

show abstract

“…This dissociation degree has been measured by power input measurements on pure H 2 arcs and has been determined to be around 70% (of the input flow) for an arc current of 37.5 A [14]. The fact that we observe (also in pure hydrogen [8,15]) a low dissociation degree inside the vessel (maximum 10%), a vessel (i.e., wall) association process must be considered. Assuming that, in the above case, 70% of the particles leaving the arc are H and D radicals, the walls must be saturated with H and D; subsequent association and desorption of molecules should lead to the observed H 2 : HD : D 2 ratio of 1 : 2 : 1.…”

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confidence: 83%