Volume recombination and opacity in Alcator C-Mod divertor plasmas

Journal Article · Fri May 01 04:00:00 EDT 1998 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.872845· OSTI ID:610671

Terry, J L; Lipschultz, B; Pigarov, A Y; Krasheninnikov, S I; LaBombard, B; Lumma, D; Ohkawa, H; Pappas, D; Umansky, M ^[1]

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1. Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139 (United States)

Volume recombination within the Alcator C-Mod [I. H. Hutchinson {ital et al.}, Phys. Plasmas {bold 1}, 1511 (1994)] divertor plasma is measured and found to be a significant fraction of the total ion sink under detached divertor conditions. The recombination occurs in regions where T{sub e}{approximately}1eV and n{sub e}{approximately}10{sup 21}m{sup {minus}3}. Measurements of the spatial distribution of the recombination are presented. The determinations of the recombination rates are made by measuring the D{sup 0} Balmer spectrum and by using a collisional radiative model describing the level populations, ionization, and recombination of D{sup 0}. The concept of {open_quotes}recombinations per Balmer series photon{close_quotes} is developed to simplify the determinations. Measurements of the opacity of Ly{sub {beta}} emission are presented. It is observed that up to 50{percent} of the Ly{sub {beta}} emission is trapped, indicating that Ly{sub {alpha}} is strongly trapped in some cases. The effects of Ly{sub {alpha},{beta}} trapping on the {open_quotes}recombinations per photon{close_quotes} curves are calculated and considered in the recombination rate determinations. Observations indicating the presence of molecular activated recombination are discussed. {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 610671
• Report Number(s): CONF-971103--
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 5 Vol. 5; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
DIVERTORS
OPACITY
PLASMA CONFINEMENT
RECOMBINATION