Optimization of the current extracted from an ultracold ion source

Debernardi, N.; Vliembergen, R.W.L. van; Engelen, W.J.; Hermans, K.H.M.; Reijnders, M.P.; Geer, S.B. van der; Mutsaers, P.H.A.; Luiten, O.J.; Vredenbregt, E.J.D.

doi:10.1088/1367-2630/14/8/083011

Cited by 21 publications

(18 citation statements)

References 22 publications

(52 reference statements)

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“…To address the time dependence in a pulsed MOTIS, Debernardi et al 145 present a model which takes into account a number of the important time scales in a MOTIS. For present purposes, we choose two limiting cases: a pulsed mode in which a very fast ionization pulse creates ions on a time scale much faster than any change in MOT population, and a continuous mode, in which a MOT operates at steady state with an ionization laser constantly ionizing atoms at a time-independent rate.…”

Section: Magneto-optical Trap-based Ion Source (Motis)mentioning

confidence: 99%

“…More recently, some in-depth studies of the ion temperature 154 and optimization of the current 145 have been reported on a Rb MOT-based cold-atom ion source. Using essentially the same apparatus as was used in the work described above, spot sizes measured on a MCP detector were combined with particle-tracking simulations to show an effective source ion temperature of (3 ± 2) mK.…”

Section: Motis Realizationsmentioning

confidence: 99%

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Bright focused ion beam sources based on laser-cooled atoms

McClelland

Steele

Knuffman

et al. 2016

Applied Physics Reviews

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Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future.

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Section: Magneto-optical Trap-based Ion Source (Motis)mentioning

confidence: 99%

Section: Motis Realizationsmentioning

confidence: 99%

Bright focused ion beam sources based on laser-cooled atoms

McClelland

Steele

Knuffman

et al. 2016

Applied Physics Reviews

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“…gives r r;i r v r ;i ¼ r r;f r v r ;f ; (13) in which r r,i and r r,f are the rms radial sizes of the beam in the ionization plane and the focus of the beam, respectively, and r v r ;i and r v r ;f are the rms spreads in radial velocity in the ionization plane and the focus of the beam, respectively. The current distribution in the ionization plane is assumed to be uniform with a radial size r i .…”

Section: Spot Size Calculationsmentioning

confidence: 99%

“…[10][11][12] The so called ultra-cold ion source (UCIS) produced a beam of ionic rubidium with a reduced brightness of 8 Â 10 4 A m À2 sr À1 eV À1 and a rms energy spread of 0.9 eV. 13 A complete FIB system was built as well, utilizing the similar magneto optical trap ion source (MOTIS). It was able to focus a 0.7 pA beam of lithium to a spot size of 27 nm.…”

Section: Introductionmentioning

confidence: 99%

Performance predictions of a focused ion beam from a laser cooled and compressed atomic beam

Haaf

Wouters

Geer

et al. 2014

Journal of Applied Physics

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Focused ion beams are indispensable tools in the semiconductor industry because of their ability to image and modify structures at the nanometer length scale. Here we report on performance predictions of a new type of focused ion beam based on photo-ionization of a laser cooled and compressed atomic beam. Particle tracing simulations are performed to investigate the effects of disorder-induced heating after ionization in a large electric field. They lead to a constraint on this electric field strength which is used as input for an analytical model which predicts the minimum attainable spot size as a function of amongst others the flux density of the atomic beam, the temperature of this beam and the total current. At low currents (I < 10 pA) the spot size will be limited by a combination of spherical aberration and brightness, while at higher currents this is a combination of chromatic aberration and brightness. It is expected that a nanometer size spot is possible at a current of 1 pA. The analytical model was verified with particle tracing simulations of a complete focused ion beam setup. A genetic algorithm was used to find the optimum acceleration electric field as a function of the current. At low currents the result agrees well with the analytical model while at higher currents the spot sizes found are even lower due to effects that are not taken into account in the analytical model.

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“…Sisyphus cooling can also be used to collimate a thermal atom beam [6], with applications in nanofabrication [7], frequency standards in atomic clocks [8], and focused ion beams [9][10][11].…”

Section: Introductionmentioning

confidence: 99%