First Use of Z-pinch-driven Ion Deflectometry for Azimuthal Magnetic Field Measurements*

Deflections of multi-MeV ions can be used for measurements of path-integrated B-fields in high-temperature plasmas. Ion deflectometry has been successfully employed in laser-produced plasmas. Ions accelerated by laser-target interactions were also utilized for a study of Z-pinch plasmas. Here, we present results of the first Z-pinch-driven ion deflectometry experiments using MeV ion beams accelerated within a hybrid gas-puff Z-pinch plasma on the GIT-12 pulse power generator. During a disruption of 3 MA current, hydrogen ions were accelerated up to 50 MeV. In our configuration, an inserted fiducial grid separated an internal ion source from studied B-fields below it. A shadow of this grid, backlighted by the ions, was distorted by the B-fields and recorded by an ion pinhole camera. Analysis of experimental images (deflectograms) provided a radial distribution of path-integrated B-fields near the axis (within a 13-mm radius). Moreover, a 2D topological map of the B(r,z) was obtained by numerical reconstruction of the deflectograms.