High-resolution measurement, line identification, and spectral modeling of the {ital K}{beta} spectrum of heliumlike Ar{sup 16+}

Journal Article · Tue Aug 01 04:00:00 EDT 1995 · Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

DOI:https://doi.org/10.1103/PhysRevE.52.1980· OSTI ID:91903

Beiersdorfer, P; Osterheld, A L; Phillips, T W ^[1]; Bitter, M; Hill, K W; von Goeler, S ^[2]

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1. Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)
2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

High-resolution crystal spectrometer measurements of the {ital K}{beta} spectrum of heliumlike Ar{sup 16+} covering the wavelength region from 3.34 to 3.50 A are presented and compared with detailed theoretical analyses. The measurements were made on the Princeton Large Torus tokamak and test the theoretical atomic data in the low-density limit at an electron density {ital n}{sub {ital e}}{le}2{times}10{sup 13} cm{sup {minus}3} and temperature {ital T}{sub {ital e}}=2.3 keV. Satellite transitions of the type 1{ital s}{sup 2}2{ital l}-1{ital s}2{ital l}3{ital l}{prime} and 1{ital s}{sup 2}3{ital l}-1{ital s}3{ital l}3{ital l}{prime} from lithiumlike Ar{sup 15+} and 1{ital s}{sup 2}2{ital l}2{ital l}{prime}-1{ital s}2{ital l}2{ital l}{prime}3{ital l}{prime}{prime} from berylliumlike Ar{sup 14+} are identified that are produced by either dielectronic recombination or electron-impact excitation. Good agreement between the predicted and measured intensities of the strong dielectronic satellites is found. The agreement demonstrates the utility of {ital K}{beta} spectra as a diagnostic of the electron temperature of low-density plasmas, such as those found in the Sun or magnetic fusion facilities. Poorer agreement is found for the weaker dielectronic satellite transitions, including the 1{ital s}3{ital l}3{ital l}{prime} satellites that play an important role in the analysis of high-density plasma produced in laser fusion. Their intensity is underestimated by the calculations by about 50%. And it is shown that direct electron-impact excitation rates underestimate the relative intensity of the 1{ital s}{sup 2} {sup 1}{ital S}{sub 0}--1{ital s}2{ital p} {sup 3}{ital P}{sub 1} transition in heliumlike Ar{sup 16+} by a factor of 2, indicating the need for including additional excitation processes and possible blends with high-lying dielectronic satellites of the type 1{ital s}{sup 2}{ital nl}{prime}-1{ital s}3{ital lnl}{prime} with {ital n}{ge}4 in the theoretical models.

• Research Organization: Lawrence Livermore National Laboratory
• DOE Contract Number: W-7405-ENG-48; AC02-76CH03073
• OSTI ID: 91903
• Journal Information: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics, Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics Journal Issue: 2 Vol. 52; ISSN PLEEE8; ISSN 1063-651X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ARGON IONS
HELIUM
ISOELECTRONIC ATOMS
K SHELL
SPECTRA
TOKAMAK DEVICES
X-RAY EMISSION ANALYSIS