Image reconstruction methods for the PBX-M pinhole camera

Technical Report · Thu Mar 01 00:00:00 EST 1990

DOI:https://doi.org/10.2172/7102065· OSTI ID:7102065

Holland, A; Powell, E T; Fonck, R J

This paper describes two methods which have been used to reconstruct the soft x-ray emission profile of the PBX-M tokamak from the projected images recorded by the PBX-M pinhole camera. Both methods must accurately represent the shape of the reconstructed profile while also providing a degree of immunity to noise in the data. The first method is a simple least squares fit to the data. This has the advantage of being fast and small, and thus easily implemented on the PDP-11 computer used to control the video digitizer for the pinhole camera. The second method involves the application of a maximum entropy algorithm to an overdetermined system. This has the advantage of allowing the use of a default profile. This profile contains additional knowledge about the plasma shape which can be obtained from equilibrium fits to the external magnetic measurements. Additionally the reconstruction is guaranteed positive, and the fit to the data can be relaxed by specifying both the amount and distribution of noise in the image. The algorithm described has the advantage of being considerably faster, for an overdetermined system, than the usual Lagrange multiplier approach to finding the maximum entropy solution. 13 refs., 24 figs.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 7102065
• Report Number(s): PPPL-2676; ON: DE90008152; TRN: 90-008200
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
PBX DEVICES
IMAGE PROCESSING
CAMERAS
LEAST SQUARE FIT
PLASMA DIAGNOSTICS
X-RAY EMISSION ANALYSIS
CHEMICAL ANALYSIS
CLOSED PLASMA DEVICES
MAXIMUM-LIKELIHOOD FIT
NONDESTRUCTIVE ANALYSIS
NUMERICAL SOLUTION
PROCESSING
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700102* - Fusion Energy- Plasma Research- Diagnostics