Alpha particle diagnostics using impurity pellet injection (invited)

Journal Article · Thu Oct 01 04:00:00 EDT 1992 · Review of Scientific Instruments; (United States)

DOI:https://doi.org/10.1063/1.1143705· OSTI ID:7259271

Fisher, R K; McChesney, J M; Howald, A W; Parks, P B ^[1]; Snipes, J A; Terry, J L; Marmar, E S ^[2]; Zweben, S J; Medley, S S ^[3]

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1. General Atomics, P.O. Box 85608, San Diego, California 92186-9784 (United States)
2. Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
3. Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

We have proposed using impurity pellet injection to measure the energy distribution of the fast confined alpha particles in a reacting plasma (R. K. Fisher {ital et} {ital al}., Fusion Technol. {bold 13}, 536 (1988)). The ablation cloud surrounding the injected pellet is thick enough that an equilibrium fraction {ital F}{sup {infinity}}{sub 0}({ital E}) of the incident alphas should be neutralized as they pass through the cloud. By observing neutrals created in the large spatial region of the cloud which is expected to be dominated by the heliumlike ionization state, e.g., Li{sup +} ions, we can determine the incident alpha distribution {ital dn}{sub He}{sup 2+}/{ital dE} from the measured energy distribution of neutral helium atoms {ital dn}{sub He{sup 0}}/{ital dE} using {ital dn}{sub He{sup 0}}/{ital dE} = {ital dn}{sub He}{sup 2+}/{ital dE}{center dot}{ital F}{sup {infinity}}{sub 0} ({ital E},Li{sup +}). Initial experiments were performed on the Texas Experimental Tokamak (TEXT) in which we compared pellet penetration with our impurity pellet ablation model (P. B. Parks {ital et} {ital al}., Nucl. Fusion {bold 28}, 477 (1988)), and measured the spatial distribution of various ionization states in carbon pellet clouds (R. K. Fisher {ital et} {ital al}., Rev. Sci. Instrum. {bold 61}, 3196 (1990)). Experiments have recently begun on the Tokamak Fusion Test Reactor (TFTR) with the goal of measuring the alpha particle energy distribution during D--T operation in 1993--94. A series of preliminary experiments are planned to test the diagnostic concept. The first experiments will observe neutrals from beam-injected deuterium ions and the high energy {sup 3}He tail produced during ion cyclotron (ICH) minority heating on TFTR interacting with the cloud. We will also monitor by line radiation the charge state distributions in lithium, boron, and carbon clouds.

• DOE Contract Number: AC03-89ER53277; FG02-90ER54084; AC02-76CH03073
• OSTI ID: 7259271
• Journal Information: Review of Scientific Instruments; (United States), Journal Name: Review of Scientific Instruments; (United States) Vol. 63:10; ISSN RSINA; ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700320* -- Plasma Diagnostic Techniques & Instrumentation-- (1992-)
ABLATION
ALKALI METALS
ALPHA SPECTRA
CHARGE EXCHANGE
CLOSED PLASMA DEVICES
ELEMENTS
ENERGY RANGE
LITHIUM
METALS
MEV RANGE
MEV RANGE 01-10
PELLET INJECTION
PLASMA DIAGNOSTICS
SPECTRA
TEXT DEVICES
TFTR TOKAMAK
THERMONUCLEAR DEVICES
TOKAMAK DEVICES