Turbulent transport in the scrape-off layer of Wendelstein 7-X

Turbulent transport is widely considered to be the main driver for cross-field transport in the scrape-off layer (SOL) of toroidal magnetized plasmas. Here, reciprocating Langmuir probes are employed to measure both the plasma profiles and the turbulent particle transport in the SOL of the Wendelstein 7-X stellarator. The relation between turbulent radial particle flux Γr and the local pressure gradient is often approximately linear across the entire SOL width, indicating that radial turbulence spreading is absent. This observation holds across a wide range of magnetic configurations and different plasma heating and density scenarios. The magnitude of the turbulent transport for a given gradient reveals a dependence on the magnetic configuration and the position in the SOL, which we relate to the cross-spectral characteristics of multi-tip floating potential measurements. Magnetic islands can add further complexity due to non-monotonic SOL profiles and the breaking of the transport-gradient relation. Finally, anomalous diffusion coefficients are determined from the probe measurements

Prototype Chip for a Control System in a Serial Powered Pixel Detector at the ATLAS Phase II Upgrade

A new inner tracking detector for the Phase-II upgrade of the ATLAS experiment is in development. A serial power scheme is foreseen for the pixel detector. This requires a new detector control system to monitor and control the pixel modules in the serial power chain. The Pixel Serial Power Protection (PSPP) chip is an ASIC for this purpose. It operates parallel to the modules and contains an ADC and bypass transistor. This paper presents test results for the prototyped PSPP chip. It includes irradiation up to 600 Mrad and longterm measurements. The third version of the PSPP chip is functional and will be used for tests with serial power chains together with pixel modules