Heavy ion beam probe advances from the first installation of the diagnostic on an RFP (invited)

Journal Article · Mon Oct 15 00:00:00 EDT 2012 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.4731758· OSTI ID:22093854

Demers, D. R.; Fimognari, P. J. ^[1]

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1. Xantho Technologies, LLC, Madison, Wisconsin 53705 (United States)

Heavy ion beam probes have been installed on a variety of toroidal devices, but the first and only application on a reversed field pinch is the diagnostic on the Madison Symmetric Torus. Simultaneous measurements of spatially localized equilibrium potential and fluctuations of density and potential, previously inaccessible in the core of the reversed field pinch (RFP), are now attainable. These measurements reflect the unique strength of the heavy ion beam probe (HIBP) diagnostic. They will help determine the characteristics and evolution of electrostatic fluctuations and their role in transport, and determine the relation of the interior electric field and flows. Many aspects of the RFP present original challenges to HIBP operation and inference of plasma quantities. The magnetic field contributes to a number of the issues: the comparable magnitudes of the toroidal and poloidal fields and edge reversal result in highly three-dimensional beam trajectories; partial generation of the magnetic field by plasma current cause it and hence the beam trajectories to vary with time; and temporal topology and amplitude changes are common. Associated complications include strong ultraviolet radiation and elevated particle losses that can alter functionality of the electrostatic systems and generate noise on the detectors. These complexities have necessitated the development of new operation and data analysis techniques: the implementation of primary and secondary beamlines, adoption of alternative beam steering methods, development of higher precision electrostatic system models, refinement of trajectory calculations and sample volume modeling, establishment of stray particle and noise reduction methods, and formulation of alternative data analysis techniques. These innovative methods and the knowledge gained with this system are likely to translate to future HIBP operation on large scale stellarators and tokamaks.

• OSTI ID: 22093854
• Journal Information: Review of Scientific Instruments, Vol. 83, Issue 10; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ACCURACY
DATA ANALYSIS
ELECTRIC FIELDS
ELECTRON DENSITY
EQUILIBRIUM
EQUIPMENT
FLUCTUATIONS
HEAVY IONS
INSTALLATION
ION BEAMS
MAGNETIC FIELDS
REVERSED-FIELD PINCH DEVICES
REVERSE-FIELD PINCH
SIMULATION
STELLARATORS
SYMMETRY
TOKAMAK DEVICES
ULTRAVIOLET RADIATION