Nuclear Instruments and Methods in Physics Research A 464 (2001) 502–511 Paul trap experiment to simulate intense nonneutral beam propagation through a periodic focusing field configuration Ronald C. Davidson*, Philip C. Efthimion, Richard Majeski, Hong Qin, Gennady Shvets Plasma Physics Laboratory, Princeton University, Princeton, NJ 08543, USA Abstract This paper describes the design concept for a compact Paul trap experimental configuration that fully simulates the collective processes and nonlinear transverse dynamics of an intense charged particle beam that propagates over large distances through a periodic quadrupole magnetic field. To summarize, a long nonneutral plasma column ðL4r p Þ is confined axially by applied DC voltages # V ¼ const: on end cylinders at z ¼L, and transverse confinement is provided by segmented cylindrical electrodes (at radius r w ) with applied oscillatory voltages V 0 ðtÞ over 908 segments. Because the transverse focusing force is similar in waveform to that produced by a discrete set of periodic quadrupole magnets in a frame moving with the beam, the Paul trap configuration offers the possibility of simulating intense beam propagation in a compact experimental facility. The nominal operating parameters in the experimental design are: barium ions ðA ¼ 137Þ; plasma column length 2L ¼ 2 m; wall radius r w ¼ 10 cm; plasma radius r p ¼ 1 cm; maximum wall voltage # V 0 ¼ 400 V; end electrode voltage up to # V ¼ 500 V; and voltage oscillation frequency f 0 ¼ 1=T ¼ 60 kHz. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Ion beam; Space charge; Stability; Transport 1. Introduction Periodic focusing accelerators and transport systems [1–5] have a wide range of applications ranging from basic scientific research in high energy and nuclear physics, to applications such as spallation neutron sources, tritium production, heavy ion fusion, and nuclear waste treatment, to mention a few examples. Of particular interest, at the high beam currents and charge densities of practical interest, are the combined effects of the applied focusing field and the intense self-fields produced by the beam space charge and current on determining detailed equilibrium, stability, and transport properties [1–5]. Through basic experi- mental studies, analytical investigations based on the nonlinear Vlasov–Maxwell equations, and numerical simulations using particle-in-cell models and nonlinear perturbative simulation techniques, considerable progress has been made in developing an improved understanding of the collective processes and nonlinear beam dynamics character- istic of high-intensity beam propagation [6–14] in periodic focusing and uniform focusing transport systems. Nonetheless, it remains important to develop an improved basic understanding of the nonlinear dynamics and collective processes in *Corresponding author. Fax: +1-609-243-2749. E-mail address: rdavidson@pppl.gov (R.C. Davidson). 0168-9002/01/$-see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(01)00118-8