Advances in neutral-beam-based diagnostics on the Madison Symmetric Torus reversed-field pinch (invited)

Journal Article · Sun Oct 15 00:00:00 EDT 2006 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.2217920· OSTI ID:20861320

Den Hartog, D J; Craig, D; Ennis, D A; Fiksel, G; Gangadhara, S; Holly, D J; Reardon, J C; Davydenko, V I; Ivanov, A A; Lizunov, A A; O'Mullane, M G; Summers, H P ^[1]

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1. Department of Physics, and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

Innovative charge-exchange recombination spectroscopy (CHERS), motional Stark effect (MSE), and Rutherford scattering diagnostics are now in operation on the Madison Symmetric Torus (MST) reversed-field pinch (RFP). The CHERS diagnostic measures impurity ion flow and temperature, localized to 2 cm with high time resolution ({approx}100 kHz). A spectral MSE diagnostic has been in use for five years, measuring |B| down to 0.2 T with high precision ({approx}2%) and good time resolution (10 kHz). The Rutherford scattering diagnostic has demonstrated the robustness of this technique for reliable measurement of majority (D) ion temperature, also with high time resolution. MST is a large RFP (R=1.5 m, a=0.52 m) operated at moderate current (I{sub p}{<=}600 kA), with n{sub e} typically (1-2)x10{sup 19} m{sup -3} and T{sub e}, T{sub i}{<=}2 keV. Two compact and reliable diagnostic neutral beams are installed on MST. These beams are short pulse, intense, monoenergetic, and low divergence. The first, a neutral H beam, is used in combination with ultraviolet and visible spectroscopy to make the CHERS and MSE measurements. For CHERS, the C VI line at 343.4 nm is collected by a custom high-throughput double grating spectrometer which simultaneously records both charge-exchange and background emissions. The spectrum is analyzed using a sophisticated model derived from the Atomic Database and Analysis Structure (ADAS) package. The MSE system records the entire H{alpha} Stark spectrum; |B| is derived from the measured splitting of the {pi}{sup +} and {pi}{sup -} manifolds. Measurement of |B| is critical to accurate equilibrium reconstruction in the RFP. The second diagnostic beam is a 20 keV neutral He beam and is used for the Rutherford scattering measurements. A pair of neutral particle analyzers is used to record the energy spectrum of the small-angle Rutherford scattered He atoms.

• OSTI ID: 20861320
• Journal Information: Review of Scientific Instruments, Vol. 77, Issue 10; Other Information: DOI: 10.1063/1.2217920; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ADA
BEAM-PLASMA SYSTEMS
BEAMS
CHARGE EXCHANGE
ENERGY SPECTRA
HELIUM
HYDROGEN
ION TEMPERATURE
NEUTRAL PARTICLE ANALYZERS
PLASMA DIAGNOSTICS
PLASMA IMPURITIES
REVERSE-FIELD PINCH
REVERSED-FIELD PINCH DEVICES
RUTHERFORD SCATTERING
SPECTROSCOPY
STARK EFFECT
TIME RESOLUTION
ULTRAVIOLET RADIATION