Speaker
Gabor Veres
(Department of Plasma Physics)
Description
Devices that are capable of measuring the total plasma radiation in fusion reactor experiments are indispensable for safe and reliable plasma operation. One of the most widespread type of these kind of devices are metal absorber–metal resistor bolometers where the radiation is absorbed by a metallic layer and the change of the layer’s temperature is measured by metal resistors. Based on the measured change of the resistance, the radiated power absorbed by the metallic layer is back-calculated. With this back-calculated power value the total plasma radiation (or spatial distribution thereof) can be deducted, once the geometrical properties of the observation (direction, solid angle, etc.) are known.
In the process of the calculation of the plasma radiative power from the change of the resistance of a metallic meander, a number of assumptions have to be made the validity of which is normally hard to prove. To ascribe a given degree of trustability to the derived plasma radiative power, the use of a fussy logic based approach is herewith proposed and implemented, where fuzzy functions are assigned to different physical and geometrical properties of the metal resistor → metal absorber → camera housing → numerical assumptions back-calculation chain. This fuzzy inference system handles such absolutely independent factors like characteristics of the metallic layer (thickness, absorption coefficient, etc.) and the geometric setup of camera (tolerances in the line-of-sight, spatial position, etc.). Our fuzzy model is tested on results of numerical plasma simulations the uncertainties of which are also handled via fuzzy functions. The resulted fuzzy system (camera + plasma) is a suitable tool to be able to estimate the overall error and uncertainty of radiation detection. In case of actual bolometers, the model can be initialized with real data and then inserted (for example) into the plasma control system.
Co-authors
Attila Piros
(Department of Machine and Product Design, Budapest University of Technology and Economics, Budapest, Hungary)
Gabor Veres
(Department of Plasma Physics, Wigner Research Centre for Physics, Budapest, Hungary)
