Generation, transport and focusing of high-brightness heavy ion beams

Abstract

The Neutralized Transport Experiment (NTX) has been built at the Heavy Ion Fusion Virtual National Laboratory. NTX is the first successful integrated beam system experiment that explores various physical phenomena, and determines the final spot size of a high intensity ion beam on a scaled version of a Heavy Ion Fusion driver. The final spot size is determined by the conditions of the beam produced in the injector, the beam dynamics in the focusing lattice, and the plasma neutralization dynamics in the final transport. A high brightness ion source using an aperturing technique delivers 25 mA of single charged potassium ion beam at 300 keV and a normalized edge emittance of 0.05 r-mm-mr. The ion beam is injected into a large bore magnetic quadrupole lattice, which produces a 20 mm radius beam converging at 20 mr. The converging ion beam is further injected into a plasma neutralization drift section where it is compressed ballistically down to a 1 mm spot size.

(cont.) NTX provides the first experimental proof of plasma neutralized ballistic transport of a space-charge dominated ion beam, the information about higher order aberration effects on the spot size, the validation of numerical tools based on excellent agreement between measurements and numerical simulations over a broad parameter regime, and the development of new diagnostics to study the ion beam dynamics. The theoretical and experimental results are presented on the beam dynamics in the ion diode, downstream quadrupole lattice, and final neutralized transport.