Drift Compression of an Intense Neutralized Ion Beam

Longitudinal compression of a velocity-tailored, intense neutralized ${\mathrm{K}}^{+}$ beam at 300 keV, 25 mA has been demonstrated. The compression takes place in a 1–2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhancing the beam peak current by a factor of 50 and producing a pulse duration of about 3 ns. This measurement has been confirmed independently with two different diagnostic systems.

Figure 1

Schematic of the NDCX experimental setup.

Figure 2

Neutralized drift-compressed beam current with the voltage waveforms in Fig. 3.

Figure 3

Induction module voltage waveforms produced by varying the timing of the modulators.

Figure 4

Experimentally optimized and ideal induction module voltage waveforms.

Figure 5

Compressed beam current pulses using a nominal tilt core voltage waveform as the beam energy is varied.

Figure 6

(a) Measurements of beam signal using the phototube diagnostic for neutralized noncompressed, and neutralized compressed beams, (b) compression ratio obtained from the measurements using the phototube, (c) compression ratio obtained from measurements using the Faraday cup, and (d) LSP (an electromagnetic particle-in-cell code) simulation for axial compression ratio under the experimental conditions.

Figure 7

Experimental data and LSP simulation of beam compression with neutralization (plasma source on) and without neutralization (plasma source off).

Figure 8

Comparison of beam compression between experiment and LSP simulation for the 2 m long plasma column.

Figure 9

Transverse profiles of neutralized compressed beam using a gated camera.