ExB analyzer for fast ion temperature measurements in scrape-off layer of the ASDEX Upgrade and COMPASS tokamaks

Abstract

Ion temperature in the scrape-off layer is an important quantity but rarely measured at high temporal resolution. In order to achieve fast measurements during intermittent events such as blobs, a novel ExB analyzer has been designed. The measurement with the E$\times$B analyzer does not require voltage sweeping but records ion current on DC biased collectors, meaning that the temporal resolution is only limited by the sampling frequency of the data acquisition system and electronics of the amplifiers, which exceeds the typical timescale of events of interest (~10 microseconds). The analyzer is equipped with entrance slit of optimized knife-edge shape, which reduces selective ion losses and improves overall ion transmission. The design of the analyzer is presented together with first acquired signals and reconstructed temperatures.