Property measurements of light ion beams for inertial confinement fusion

There are assumed that the divergence growth origin from an ion transit time coupling to dioctron instability in the electron sheath is different in directions parallel (azimuthal) and perpendicular (radial) to ExB drift direction. In order to observe divergence change with time in parallel and perpendicular to the ExB drift direction, the two-dimensional APC are developed. The two-dimensional APC method enable observing divergence and intensity distributions simultaneously with ∼10 ns time resolution. Measured ion beam by the APC is a hollow beam, generated from the two-stage applied-B type ion diode with passive ion source driven by Reiden-SHVS pulsed power machine. Experimental results show that the divergence in parallel to ExB growth with time in contrary that the divergence in perpendicular to ExB show nearly constant values with time changes. In order to improve spatial uniformity of ion beams, changing the magnetic field configuration of the first stage of the diode are tried. The evaluation of the beam uniformity is done by the APC measurements. A more uniform condition is found at reduced inner magnetic field that means non-uniform-B condition at the anode surface. (author)