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Edge localised modes (ELMs) are a serious concern for plasma facing components in next generation tokamaks. Due to the limited capabilities of the commonly used bolometers reliable radiation data are generally only available with a time resolution of a few milliseconds, which is much larger than the power deposition time of type-I ELMs. Therefore an improved evaluation algorithm for bolometric data has been developed which allows to calculate the radiated energy on type-I ELM relevant timescales and to tomographically reconstruct the spatial distribution of the radiated energy during an ELM. This method has been used to investigate radiation during type-I ELMs in various plasma configurations. The spatial distribution of the radiated energy during an ELM shows that radiation losses are mainly located in the divertor. Up to 40% of the ELM energy loss are found as radiation. The energy balance is nearly fulfilled in most cases.

Radiation distribution and heat load on the target plates of ASDEX Upgrade are investigated over a wide experimental parameter range with discharges up to 20 MW heating power and n e =(0.4–0.8)n GW . Integrating the radiation density over the whole plasma yields a total radiated power of about 80% of the input power, and radiation from the divertor and X-point region is about 40% of the input power. Whereas the radiated power in the main plasma is comparable for the former open divertor I (Div I) and the new closed LYRA divertor (Div II), the radiation fraction in the divertor has nearly doubled for the LYRA divertor. Simultaneous to the increased divertor radiation in the LYRA divertor, the maximum heat flux density to the target plates, measured by thermographic cameras, is reduced by a factor of about two compared to that in Div I for comparable attached conditions. Furthermore, especially in the inner divertor fan, the radiation contributes to a large part of the measured heat flux.

We report on an investigation of a photoresponse induced in a novel, miniaturized low-noise metal resistor film bolometer when irradiated by ultrashort laser pulses (duration 100 ps to 200 ns) with wavelengths covering the mid- and far-infrared spectral ranges. Successful operation at room temperature was achieved and almost constant detectivity was found over the whole frequency range investigated (15–1100 cm−1). The minimum detectable laser pulse energy was determined to be about 0.6 μ J (with an electronic bandwidth of 1 kHz). This high detectivity and the miniaturized dimensions afford the possibility of building detector arrays applicable in mid- and far-infrared spectroscopy.