A new method of out-of-focus millimeter wave imaging in fusion plasma diagnostics using Bessel beams
Electron cyclotron emission imaging (ECEI) and microwave imaging reflectometry diagnostics have been employed on a number of magnetic fusion plasma confinement devices. The common approach is based on a Gaussian beam assumption, which generates good spatial resolution (centimeter level). However, the radial focal depth is limited by the poloidal resolution, which is comparable with the Rayleigh length (~150 mm). By contrast, a new Bessel beam approach has been developed and demonstrated to generate much longer focal depth with the property of propagation stability. To test the new approach, the DIII-D tokamak LCP ECEI optics have been re-designed to support a Bessel beam approach based on an axicon lens. The achievable radial coverage can exceed that of the current Gaussian approach by 3×. Finally, the imaging result is discussed in this paper based on the simulation analysis and laboratory testing result.
- Research Organization:
- Univ. of California, Davis, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- Grant/Contract Number:
- SC0012551
- OSTI ID:
- 1540147
- Alternate ID(s):
- OSTI ID: 1473740
- Journal Information:
- Review of Scientific Instruments, Vol. 89, Issue 9; ISSN 0034-6748
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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