Ion sources, systems and methods
Ion sources, systems and methods are disclosed. In some embodiments, the ion sources, systems and methods can exhibit relatively little undesired vibration and/or can sufficiently dampen undesired vibration. This can enhance performance (e.g., increase reliability, stability and the like).
1. A field emission charged particle source, comprising:
an outer structure mounted to a carrying structure being at environmental temperature, the outer structure comprising a material having a thermal conductivity;
an intermediate structure mounted to the outer structure, the intermediate structure comprising a material having a thermal conductivity;
an inner structure mounted to the intermediate structure, the inner structure comprising a material having a thermal conductivity;
a charged particle field emitter mounted to the inner structure; and
a cooling device thermally connected to the intermediate structure,
wherein:
the outer structure comprises a material having a lower thermal conductivity than the material of the inner structure, and/or the material of the intermediate structure has a thermal conductivity that is larger than 1.5 times the thermal conductivity of the material of the outer structure;
the cooling device is thermally connected to the intermediate structure along a first bundle of thermally conducting, flexible wires; and
the cooling device is connected to the intermediate structure along a second bundle of flexible wires and along one or more rigid rods.
2. The field emission charged particle source of claim 1 , wherein the outer structure has a first wall thickness, the inner structure has a second wall thickness, and the first wall thickness is less than the second wall thickness.
3. The field emission charged particle source of claim 1 , wherein the inner structure comprises copper and the outer structure comprises stainless steel.
4. The field emission charged particle source of claim 1 , wherein the outer structure has a cylindrical shape with a first diameter, the inner structure has a cylindrical shape with a second diameter, and the second diameter is less than the first diameter.
5. The field emission charged particle source of claim 1 , wherein the one or more rigid rods are arranged, in series, between the first and the second bundle of thermally conductive flexible wires.
6. The field emission charged particle source of claim 1 , wherein the first and/or the second bundle of flexible wires comprise copper.
7. The field emission charged particle source of claim 1 , wherein the first and/or the second bundle of flexible wires comprise a carbonated pitch material.
8. The field emission charged particle source of claim 1 , wherein the one or more rigid rods comprise copper.
9. The field emission charged particle source of claim 1 , further comprising an extraction electrode electrically isolated from the field emitter.
10. The field emission charged particle source of claim 1 , wherein the field emitter is mounted to the inner structure via a material with a thermal conductivity which is greater than the thermal conductivity of the material of the outer structure.
11. The field emission charged particle source of claim 1 , further comprising a gas conducting tube configured to feed a gas to a region within the inner structure, wherein the gas conducting tube terminates in an intermediate region between the outer and the inner structures, and the inner structure comprises holes configured to provide a gas flow from the intermediate region to a region surrounded by the inner structure.
12. The field emission charged particle source of claim 11 , further comprising a control configured to switch off the cooling device for a defined period of time.
13. The field emission charged particle source of claim 12 , wherein the cooling device is thermally connected to the intermediate structure isothermically.
14. The field emission charged particle source of claim 13 , wherein the inner structure is a cylinder, the intermediate structure is a ring, and the cooling device is thermally connected to the intermediate structure along a series of connection regions which are arranged along the intermediate structure.
15. The field emission charged particle source of claim 1 , wherein the outer structure comprises a material having a lower thermal conductivity than the material of the inner structure.
16. The field emission charged particle source of claim 15 , wherein the material of the intermediate structure has a thermal conductivity that is larger than 1.5 times the thermal conductivity of the material of the outer structure.
17. The field emission charged particle source of claim 11 , wherein the material of the intermediate structure has a thermal conductivity that is larger than 1.5 times the thermal conductivity of the material of the outer structure.
18. A gas field beam system, comprising:
a field emission charged particle source according to claim 1 , the field emission charged particle being configured to generate a beam of charged particles with a main direction of propagation;
a scanning system configured to deflect the beam of charged particles in a direction perpendicular to the main direction of propagation; and
a control system configured to operate the field emission charged particle source, the control system being configured to provide at least a first mode of operation and a second mode of operation,
wherein:
in the first mode of operation, the cooling device is operated to cool the field emitter;
in the second mode of operation, the cooling device is off; and
in the second mode of operation, the scanning system is operated so that the beam is deflected to scan a sample.