Magneto-optical trap ion source
View Patent ↗A system and method are disclosed for producing a source of ions, and particularly, a focused ion beam. The system and method use a magneto-optical trap (MOT) to produce a population of neutral atoms. A laser is then utilized to ionize atoms and produce a population of ions. An extraction element is then used to transfer the ions so that they can be used in a wide array of applications.
1. A system for producing an ion source, the system comprising:
a magneto-optical trap having an enclosure, a component providing a magnetic field, and at least one laser, the magneto-optical trap adapted to produce a confined population of low temperature neutral atoms within the enclosure;
a secondary laser adapted to emit and direct light to at least a portion of the confined population of neutral atoms, wherein the light from the secondary laser ionizes at least a portion of the neutral atoms to thereby form a population of ions; and
an extraction element adapted to transfer the population of ions from the enclosure, and thereby produce the ion source.
2. The system of claim 1 wherein the component for providing a magnetic field includes current carrying coils which upon passing an electrical current therethrough, generate the magnetic field.
3. The system of claim 1 wherein the component for providing a magnetic field includes at least one permanent magnet.
4. The system of claim 1 , wherein the extraction element is also adapted to form the transferred population of ions into a beam.
5. The system of claim 1 , wherein the extraction element is an electrode disposed at least partially within the enclosure, the electrode being at a negative electrical potential with respect to ground, whereby an electric field is generated within the enclosure to thereby extract the population of ions and transfer the ions from the enclosure.
6. The system of claim 1 wherein the extraction element includes:
a first electrode;
a second electrode spaced from the first electrode;
wherein the first and second electrodes are disposed such that the confined population of neutral atoms is between the first and second electrodes, the first electrode defining an aperture through which at least a portion of the population of ions passes.
7. The system of claim 6 wherein the first electrode includes a reflective layer.
8. The system of claim 6 wherein the second electrode is transparent.
9. The system of claim 6 wherein the first electrode and the second electrode are each electrically biased such that the resulting electric field extracts ions from the system.
10. The system of claim 1 wherein the system produces a continuous ion beam.
11. The system of claim 1 wherein the system produces a series of ion beam pulses.
12. The system of claim 1 further comprising:
a source of neutral atoms, the source adapted to introduce the neutral atoms into the magneto-optical trap, the neutral atoms selected from the group consisting of (i) light elements, (ii) heavy elements, (iii) metals, and (iv) doping elements.
13. The system of claim 12 wherein the neutral atoms of the source is a light element selected from the group consisting of He, Li, Be and B.
14. The system of claim 12 wherein the neutral atoms of the source is a heavy element selected from the group consisting of Ar, Kr, and Xe.
15. The system of claim 12 wherein the neutral atoms of the source is a metal selected from the group consisting of Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Cr, Ag, and Er.
16. The system of claim 12 wherein the neutral atoms of the source is a doping element selected from the group consisting of Si, P, and Sb.
17. The system of claim 1 wherein the magneto-optical trap, the secondary laser, and the extraction element constitute a first ion beam generating system, the system further comprising a second ion beam generating system provided in parallel with the first ion beam generating system, the second ion beam generating system including a second magneto-optical trap, a second secondary laser, and a second extraction element, whereby the first ion beam generating system and the second ion beam generating system provide ion beams in parallel.
18. An array for providing a plurality of ion beams, the array comprising:
a plurality of ion beam generating systems, each system including (i) a magneto-optical trap having an enclosure, a component providing a magnetic field, and at least one laser, the magneto-optical trap adapted to produce a confined population of low temperature neutral atoms within the enclosure; (ii) a secondary laser adapted to emit and direct light to at least a portion of the confined population of neutral atoms, wherein the light from the secondary laser ionizes at least a portion of the neutral atoms to thereby form a population of ions; and (iii) an extraction element adapted to transfer the population of ions from the enclosure, and thereby produce an ion source.
19. A method for producing a source of ions, the method comprising:
providing (i) a magneto-optical trap having an enclosure, a component for providing a magnetic field, and a plurality of lasers, (ii) a secondary laser, and (iii) an extraction element;
operating the magneto-optical trap to produce a confined population of low temperature neutral atoms within the enclosure;
operating the secondary laser to emit light to at least a portion of the confined population of neutral atoms, the laser configured so that the light emitted therefrom ionizes at least a portion of the neutral atoms to thereby form a population of ions; and
operating the extraction element to transfer at least a portion of the population of ions from the enclosure to thereby produce a source of ions.
20. The method of claim 19 wherein the operating of the extraction element is performed by applying an electrical potential to the extraction element with respect to ground, to thereby generate an electric field within the enclosure and extract the population of ions and transfer them from the enclosure.