Operation of probe heads on the Multi-Purpose-Manipulator at W7-X in OP 1.2a

Abstract

The MultiPurpose -Manipulator (MPM) has been operated, as a versatile carrier system for probes, since the first campaign OP. 1.1 in 2015 at Wendelstein 7X. The MPM is mounted at the outboard midplane and is able to perform fast plunges through the entire scrape off layer up to the last closed flux surface. In addition, a system for gas injection was commissioned that allowed the use of a dedicated probe head and a port on the existing probes for fueling and impurity seeding experiments. A combined probe, a combination of Langmuir, Mach and magnetic probes, was used. For the second campaign OP. 1.2a in 2017, with an island divertor, an upgraded combined probe, a fluctuation probe, a retarding field analyzer, a Mach probe array, a laser blow off target and a material probe holder were added to the range of plasma edge diagnostics. The new diagnostic probe heads were designed to address specific tasks, such as measuring the edge fluctuations, the ion temperature and the radial Mach number profiles. However, all fast plunging probes were designed such that they provide the most important quantities for SOL characterization (electron temperature, density, radial electric field).

Retarding field analyzer for the wendelstein 7-X boundary plasma

“…The MPM is located in the outer mid-plane with 𝑍𝑍 = −171 mm and toroidal angle φ=-159.26 o , in between the characteristic bean shaped and triangular cross section. A variety of diagnostic probes [14][15][16] mounted on the MPM have been developed for the measurements of edge profiles like the edge electron temperature and density, and the plasma flow. To measure the edge ion temperature, an RFA prototype has been first tested on EAST.…”