Dual Langmuir-probe array for 3D plasma studies in TORPEX

We have designed and installed a new Langmuir-probe (LP) arraydiagnostic to determine basic three-dimensional (3D) features ofplasmas inTORPEX. Thediagnostic consists of two identical LP arrays, placed on opposite sides of the apparatus, which provide comprehensive coverage of the poloidal cross section at the two differenttoroidal locations. Cross correlation studies of signals from the arrays provide a basic way to extract 3D information from theplasmas, as experiments show. Moreover, the remarkable signal-to-noise performance of the front-endelectronics allows us to follow a different approach in which we combine information from all probes in both arrays to reconstruct elementary 3Dplasma structures at each acquisition time step. Then, through data analysis, we track the structures as they evolve in time. The LP arrays include a linear-motion mechanism that can displace radially the probes located on the low field side for experiments that require fine-tuning of the probe locations, and for operational compatibility with the recently installed in-vesseltoroidal conductor.
Source: Review of Scientific Instruments - Category: Physics Authors: Source Type: research