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Pulsed Heating to Extend Ion Source Lifetime and Gate Ion Current





Joe Kwan and Pavel Ni of Berkeley Lab have developed a technology to lengthen the lifetime of accelerator ion sources and gate beam current using laser light. In this approach, ion emission is achieved by heating the ion source above the emission threshold temperature with pulsed laser light. During the standby time, the ion source remains cold (below threshold temperature) and therefore, does not lose stored ions.

As an added benefit, this approach lowers the average temperature of the hot plate, requiring less complex thermal management of the injector. Because the ion current is available as long as the laser beam is on, the technology also eliminates the need for pulsed power beam current gating hardware. In other words, the laser pulse acts as the gate.

Using this technology, it would be possible to shrink, to tabletop size, an accelerator used to precisely implant alkali ions into battery electrodes, cutting battery manufacturing costs. Similar applications can be found in any field requiring ion implantation. This technology could be used in ion beam lithography over a large area, enabling the ion source to last longer because it would only emit ions where the laser hits.

Currently, ion sources are heated to fixed, high temperatures to be ready for the fraction of a second when an ion bunch is extracted and fed into the accelerator. However, a significant portion of ions is lost during the standby time. The typical lifetime of an ion source depends on the ion species. While some, such as a potassium source, can last for hundreds of hours, a lithium ion source is depleted in about 50 hours, necessitating replacement every week.

STATUS:  Available for licensing or collaborative research.

DEVELOPMENT STAGE:  The technology has been demonstrated, with high repeatability of the data, on Berkeley Lab’s Neutralized Drift Compression Experiment-II accelerator (lithium-doped alumino-silicate (Al-Si) hot-plate surface-ionization ion source). A maximum current density of 0.8 mA/cm2was achieved using a low power infrared laser (approx. 115 W/cm2) with a 2.8 mm diameter source.

Ni, P. A., Kwan, J. W., Roy, P. K., Waldron, W. L. “Li+ ion emission from a hot-plate alumina-silicate source stimulated by flash heating with an infrared laser,” Review of Scientific Instruments, 82, 023304 (2011).


Fast Pulsed Neutron Generator, IB-2752


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Last updated: 05/03/2013