Low energy H- beam transport using an electrostatic quadrupole focusing system

An experiment is designed to transport a round and diverging H- beam, with beam current of 30 mA and voltage of 35 kV, over a length of about 30 cm with the aim to match it to an RFQ with a modest emittance growth. The low energy beam transport system consists of six electrostatic quadrupole (ESQ) lenses. A linear KV code, in conjunction with a 3-D Laplace solver, is used to configure the electrode geometry. Fringe field integrals from the Laplace solver are given as input to a modified PARMILA code to evaluate the influence of the nonlinear forces and calculate the emittance growth. The ESQ system is designed with a mechanical tolerance of < 1 mil; the critical issue of alignment of the apparatus with respect to the beam is addressed. Details on the design and construction of the ESQ system and some preliminary experimental results are presented