A contribution to the magnetic focusing in an applied-B-extractor ion diode by a laser pulse driven solenoid

To obtain well focused beams is one of the key problems in light ion beam driven inertial confinement fusion. Extractor diodes with externally applied magnetic field show at present divergences of about 17 mrad. This work investigates. the possibility of improving the focusing by applying a magnetic field in the vicinity of the focus which is generated by an intense laser beam. The focusing properties of the diode are simulated using a quasi-stationary 2.5-dimensional particle-in-cell code. The applied magnetic field which is needed as input to the PIC-code is computed by PROFL The simulations show that the effect of the suggested solenoid is indeed an improvement of the focusing both for beams with a Gaussian distribution of divergence angles and for beams with an energy distribution taken from an actual experiment.