Omegatron mass spectrometer for analysis of ion concentrations in hydrogenic plasmas

Journal Article · Mon Jan 01 04:00:00 EST 2001 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1310594· OSTI ID:40204829

Hollmann, E M; Antar, G; Doerner, R P; Luckhardt, S C

We describe an omegatron-type mass spectrometer used for measurement of the molecular and atomic ion concentrations as well as the ion species temperatures in hydrogenic plasmas. The experiments were performed in the PISCES-A linear plasma experiment with electron densities n{approx}10{sup 11}--10{sup 12}cm{sup -3}, ion temperatures T{sub i}{approx}2--8eV, electron temperatures T{sub e}{approx}3--30eV, and magnetic fields B=0.8--1.9kG. The resulting mass spectra show clear evidence of atomic hydrogen H{sup +}, as well as of the molecular ions H{sub 2}{sup +} and H{sub 3}{sup +}, with H{sup +} and H{sub 3}{sup +} usually being dominant. It is found that large electron repeller voltages ({approx}-200 V) are important for preventing electrons from entering the diagnostic region and ionizing the residual gas. The relative peak heights for the different ions are found to vary as a function of ion repeller voltage, probably due to differences in ion temperature.

• Sponsoring Organization: (US)
• OSTI ID: 40204829
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 72; ISSN 0034-6748
• Publisher: The American Physical Society
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ATOMIC IONS
ELECTRON TEMPERATURE
ELECTRONS
HYDROGEN
ION TEMPERATURE
MAGNETIC FIELDS
MASS SPECTRA
MASS SPECTROMETERS
MOLECULAR IONS
PHYSICS
PLASMA