Deuterium-deuterium neutron generators
Various embodiments include apparatus and methods of using the apparatus having a neutron generator. The neutron generator can include a neutron generator tube having a cylindrical inner surface that bounds a cylindrical cavity, a field ionization array cylindrically distributed on the cylindrical inner surface, and a target rod positioned in the cylindrical cavity. Additional apparatus, systems, and methods are disclosed.
1. An apparatus comprising:
a neutron generator tube having a cylindrical inner surface that bounds a cylindrical cavity;
a deuterium source that provides deuterium within the cylindrical cavity;
a target rod positioned in the cylindrical cavity, wherein the target rod comprises a rod material and a first material layer disposed on the rod material, wherein the first material layer has a thermal conductivity less than copper, and wherein the target rod has a second material layer disposed on the first material layer; and
a field ionization array cylindrically distributed around the cylindrical inner surface.
2. The apparatus of claim 1 , wherein the target rod is positioned along an axis of symmetry of the neutron generator tube at a center of the cylindrical cavity.
3. The apparatus of claim 1 , wherein the field ionization array comprises a bundle of nano-emitters.
4. The apparatus of claim 3 , wherein the bundle of nano-emitters comprises at least one of tungsten nano-tips and carbon nano-fibers.
5. The apparatus of claim 1 , wherein the first material layer include one or more transition metals.
6. The apparatus of claim 5 , wherein the one or more transition metals include one or more of titanium and erbium.
7. The apparatus of claim 1 , wherein the neutron generator tube is disposed in a housing configured for a wireline deployment.
8. The apparatus of claim 1 , wherein the neutron generator tube is disposed in a housing configured for a logging-while-drilling deployment.
9. The apparatus of claim 1 , further comprising a suppressor grid, wherein the suppressor grid is positioned concentrically around the target rod.
10. The apparatus of claim 1 , further comprising an electric insulator disposed between the deuterium source and the target rod.
11. A method comprising:
generating neutrons into a formation around a borehole using an apparatus comprising,
a neutron generator tube comprising a cylindrical inner surface that bounds a cylindrical cavity,
a deuterium source that provides deuterium within the cylindrical cavity,
a target rod positioned in the cylindrical cavity, wherein the target rod comprises a rod material and a first material layer disposed on the rod material, and wherein the target rod has a second material layer disposed on the first material layer, and
a field ionization array cylindrically distributed around the cylindrical inner surface; collecting signals in response to generating the neutrons; and
determining properties of the formation or the borehole based on the collected signals.
12. The method of claim 11 , wherein using the neutron generator tube includes using a bundle of nano-emitters as part of the field ionization array.
13. The method of claim 11 , further comprising disposing the neutron generator tube in a wireline housing.
14. The method of claim 11 , further comprising disposing the neutron generator tube in a logging-while-drilling housing.
15. The method of claim 11 , wherein generating neutrons comprises applying a voltage pulse to a field ionization electrode attached to the field ionization array, wherein the voltage pulse is less than 120 kilovolts, and wherein the voltage pulse produces a monatomic deuterium ratio greater than or equal to 50%.
16. The method of claim 11 , wherein generating neutrons comprises applying a turn-on/turn-off time delay of the field ionization array that is less than 1 microsecond.
17. An apparatus comprising:
a neutron generator tube having a cylindrical inner surface that bounds a cylindrical cavity;
a deuterium source that provides deuterium within the cylindrical cavity;
a target rod positioned in the cylindrical cavity, wherein the target rod comprises a rod material, a first material layer disposed on the rod material, and a second material layer disposed on the first material layer; and
a field ionization array cylindrically distributed around the cylindrical inner surface.
18. The apparatus of claim 17 , wherein the target rod is positioned along an axis of symmetry of the neutron generator tube at a center of the cylindrical cavity.
19. The apparatus of claim 17 , wherein the field ionization array comprises a bundle of nano-emitters.
20. The apparatus of claim 17 , wherein the first material layer comprises one or more transition metals.