Modeling of Ionization in a Spherical Surface Ionizer

Abstract

A Monte Carlo method-based model of a hot cavity surface ion source with a spherically shaped ionizer is presented. A numerical code enables studies of ion source efficiency as a function of an extraction voltage, geometry of the ionizer and its temperature, the size of extraction aperture and many other factors. The calculation results for a variety of mentioned parameters are presented. A novel configuration of surface ion source is proposed and discussed -the efficiency of the source with an almost spherically shaped ionizer could be much higher than that of currently used constructions of ion sources.

Ionisation Efficiency in Conical Hot Cavities

“…This is also pointless in the light of the presented data. The shape of the curves is similar to that obtained in the simulations for the spherical [17] and tubular [13] ionisers. It also resembles the experimental curves obtained for the tubular ioniser case [22].…”

“…The model enabled studies of ion source efficiency as a function of many factors, like ioniser temperature, extraction voltage, timescales governing diffusion and effusion processes, as well as radioactive decay half-life. The ionisation calculations were performed for both tubular ioniser geometry and the spherical shapes [17,18], which * corresponding author; e-mail: mturek@kft.umcs.lublin.pl proved to be very effective, especially in the case of shortlived isotopes.…”

Calculations of Ion Beam Emittance for Hot Cavity Ion Source

“…Initially the model was suitable for stable and long-lived isotopes, but radioactive decay and delays due to the diusion and eusion were implemented [12,19], making it useful also for short-lived isotopes, which are common in on-line nuclear spectroscopy. Mainly tubular cavities were considered, but the model was extended to spherical cavities [20], which are employed in experiments [21,22].…”

“…Dependences of beam emittance on nuclide surface ionization probability, halflife period and its average sticking time are presented and discussed. Two dierent shapes of the ionizer cavity are considered as in [20]. Inuence of the extraction * e-mail: mturek@kft.umcs.lublin.pl opening geometry (i.e.…”

Surface Ionization of Radioactive Nuclides - Numerical Simulations

“…Recently, both theoretical [10], and numerical models of ionizations have been developed [11,12] based on the conception that high ionization eciency is an eect of multiple collisions with hot ionizer walls, and also electron impact ionization [13]. The model enabled the studies of ionization eciency as a function of many factors, ionizer geometry (including the spherical one [14]), extraction system properties, ionizer temperature, ionizer/ sample combination etc. However, the model was adequate mostly for stable or long-lived isotopes, as it did not take into account the eects of radioactive decay of nuclides during their stay in the ion source, which restricted severely its usefulness in the eld of nuclear * e-mail: mturek@kft.umcs.lublin.pl spectroscopy.…”