Action-angle formulation of generalized, orbit-based, fast-ion diagnostic weight functions

Journal Article · Mon Aug 14 00:00:00 EDT 2017 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4990391· OSTI ID:1474286

Stagner, L.  ^[1]; Heidbrink, W. W. ^[1]

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1. Univ. of California, Irvine, CA (United States)

Due to the usually complicated and anisotropic nature of the fast-ion distribution function, diagnostic velocity-space weight functions, which indicate the sensitivity of a diagnostic to different fast-ion velocities, are used to facilitate the analysis of experimental data. Additionally, when velocity-space weight functions are discretized, a linear equation relating the fast-ion density and the expected diagnostic signal is formed. In a technique known as velocity-space tomography, many measurements can be combined to create an ill-conditioned system of linear equations that can be solved using various computational methods. However, when velocity-space weight functions (which by definition ignore spatial dependencies) are used, velocity-space tomography is restricted, both by the accuracy of its forward model and also by the availability of spatially overlapping diagnostic measurements. In this work, we extend velocity-space weight functions to a full 6D generalized coordinate system and then show how to reduce them to a 3D orbit-space without loss of generality using an action-angle formulation. Moreover, we show how diagnostic orbit-weight functions can be used to infer the full fast-ion distribution function, i.e., orbit tomography. In depth derivations of orbit weight functions for the neutron, neutral particle analyzer, and fast-ion D-α diagnostics are also shown

• Research Organization: Princeton Univ., NJ (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-09CH11466; FC02-04ER54698
• OSTI ID: 1474286
• Alternate ID(s): OSTI ID: 1374930
• Journal Information: Physics of Plasmas, Vol. 24, Issue 9; ISSN 1070-664X
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS