In:
Physics of Plasmas, AIP Publishing, Vol. 29, No. 11 ( 2022-11-01)
Abstract:
We have proposed a new method to estimate the optical escape factor (OEF) in high-density helium (He) plasma. Plasma with an electron temperature of ca. 3 eV and density of 5 × 1013 cm−3 was generated by a cascaded arc discharge and rapidly cooled by the introduction of additional He gas, which resulted in a transition from ionizing to recombining plasma. With an increase in the gas pressure, the plasma became optically thick, and the He I forbidden line (spin-exchange intercombination line, 1 1S-2 3P: 59.1 nm) with resonance lines were simultaneously observed using a vacuum ultraviolet spectrometer. Comparison of the intensity ratio of the He I 58.4 nm resonance line to the forbidden emission with those by determined from the collisional-radiative model considering the self-absorption enabled the successful estimation of the OEF. The OEF was decreased with the ambient He gas pressure and was 6.6 × 10−4 and 3.5 × 10−5 for He gas pressures of 1.59 and 20.22 Pa, respectively.
Type of Medium:
Online Resource
ISSN:
1070-664X
,
1089-7674
Language:
English
Publisher:
AIP Publishing
Publication Date:
2022
detail.hit.zdb_id:
1472746-8
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