Conceptual Design of a Heavy Ion Beam Probe for Studying Optimized Stellarator Physics in the Wendelstein 7-X

Experimental measurements of characteristics in the plasma interior of Wendelstein 7-X (W7-X) are essential to increasing our understanding of optimized stellarator physics. The dynamics of particle and energy transport is an area of particular importance and, while much is inferred using power and particle balance estimates, a critical need for experimental assessment remains. A heavy ion beam probe (HIBP) can help fill this need and the design of one for W7-X is maturing, with substantial progress toward the critical milestone of a conceptual design review. The 2 MeV HIBP will acquire simultaneous, multipoint measurements of key quantities including the electric potential, and fluctuations of electron density and potential in the plasma interior. These will enable inference of the radial electric field, wavenumbers, and electrostatic fluctuation induced particle flux. We will present: anticipated measurement characteristics, predicted via simulations of beams through W7-X plasmas; status of the conceptual design, including CAD schematics of the system; characterization of key components such as the energy analyzer; an overview of project plans; and opportunities for collaboration.