Broad ion energy distributions in helicon wave-coupled helium plasma

Dataset · Fri Jan 11 04:00:00 EST 2019

DOI:https://doi.org/10.7910/DVN/5RP3KQ· OSTI ID:1881218

Woller, K. B. ^[1]; Whyte, D. G.; Wright, G. M.

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1. OSTI

Helium ion energy distributions were measured in the helicon wave-coupled plasma of the DIONISOS experiment with a retarding field energy analyzer. The shape of the energy distribution is double-peaked, characteristic of RF plasma potential modulation. The broad distribution is located within a radius of 0.8 cm while the quartz tube of the plasma source has an inner radius of 2.2 cm. The ion energy distribution rapidly changes from double-peaked to a single peak in the radius range of 0.7 to 0.9 cm. The average ion energy is approximately uniform across the plasma column including the double-peaked and single peak regions. The widths of the broad distribution, dE, in the wave-coupled mode are large compared to the time-averaged ion energy, . On axis (r = 0), dE/ ~ 3.4, and at a radius near the edge of the plasma column (r = 2.2 cm), dE/ ~1.2. The discharge parameter space is scanned to investigate the effects of magnetic field, input power, and chamber fill pressure on the wave-coupled mode that exhibits sharp radial variation in the ion energy distribution.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• DOE Contract Number: FC02-99ER54512; SC0002060
• OSTI ID: 1881218
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY