Fabrication of high gradient insulators by stack compression
Individual layers of a high gradient insulator (HGI) are first pre-cut to their final dimensions. The pre-cut layers are then stacked to form an assembly that is subsequently pressed into an HGI unit with the desired dimension. The individual layers are stacked, and alignment is maintained, using a sacrificial alignment tube that is removed after the stack is hot pressed. The HGI's are used as high voltage vacuum insulators in energy storage and transmission structures or devices, e.g. in particle accelerators and pulsed power systems.
1. A method of making a high gradient insulator (HGI) having a desired cross-section and height, comprising:
providing a plurality of conductor layers and of dielectric layers, each layer having the desired cross-section of the HGI;
providing an alignment tube;
stacking alternating conductor layers and dielectric layers, each with the desired cross-section, in or around the alignment tube to form a stacked assembly of substantially the desired height;
bonding the stacked assembly of alternating conductor layers and dielectric layers together while stacked in or around the alignment tube;
removing the alignment tube from the bonded stacked assembly to form the HGI.
2. The method of claim 1 further comprising placing the alignment tube on a lower pressure plate prior to stacking the alternating layers, and placing an upper pressure plate on top of the stacked assembly of alternating layers prior to bonding.
3. The method of claim 1 wherein the conductor layers are formed of metals or alloys and the dielectric layers are formed of plastic or ceramic.
4. The method of claim 1 wherein the plurality of conductor layers and of dielectric layers are each provided by cutting from sheets of conductor material and dielectric material respectively.
5. The method of claim 1 wherein the plurality of conductor layers and of dielectric layers are each provided by stamping from sheets of conductor material and dielectric material respectively.
6. The method of claim 1 wherein the layers of conductor and dielectric materials have a circular disc shape and are stacked in the alignment tube.
7. The method of claim 6 wherein the inner diameter of the alignment tube is selected to snuggly but slidably receive the alternating conductor and dielectric layers.
8. The method of claim 1 wherein the layers of conductor and dielectric materials have an annular shape and are stacked around the alignment tube.
9. The method of claim 8 wherein the outer diameter of the alignment tube is selected to snuggly but slidably receive the alternating conductor and dielectric layers along its outer surface.
10. The method of claim 1 wherein the alignment tube has an outward taper or an inward taper along its top edge to facilitate stacking of the layers in or around the alignment tube respectively.
11. The method of claim 1 wherein the alignment tube has a dual inward and outward taper along its top edge to facilitate stacking of the layers either in or around the alignment tube.
12. The method of claim 1 wherein the stacked assembly of layers is bonded together by hot pressing.
13. The method of claim 1 wherein the alignment tube is removed by dissolving the alignment tube in an acid that is chosen to dissolve the alignment tube rapidly and to not attack the metal layers in the HGI.
14. The method of claim 1 further comprising placing the alignment tube on a bottom pressure plate prior to stacking alternating layers of conductor and dielectric layers in or around the alignment tube.
15. The method of claim 14 further comprising placing a top pressure plate on the last layer of the stacked assembly of layers prior to bonding the stacked layers, the top pressure plate having the same cross-section as the layers.
16. The method of claim 15 wherein bonding the stacked layers together further comprises applying pressure to the top and bottom pressure plates while heating the stacked assembly of layers.
17. The method of claim 1 wherein the conductor and dielectric layers have a noncircular cross-section, and the alignment tube has a similar shape.
18. The method of claim 1 wherein the alignment tube is conical in shape, and the alternating conductor and dielectric layers have diameters that vary along the height of the alignment tube to form a conical HGI.
19. The method of claim 1 wherein the layers of conductor and dielectric materials have an annular shape, the dielectric layers having a larger outer diameter than the conductor layers, and are stacked around the alignment tube to form an HGI having the dielectric layers protruding outwardly beyond the conductor layers.
20. The method of claim 1 wherein the layers of conductor and dielectric materials have an annular shape, the dielectric layers having a smaller inner diameter than the conductor layers, and are stacked in the alignment tube to form an HGI having the dielectric layers protruding inwardly beyond the conductor layers.
21. A high gradient insulator (HGI) formed by the method of claim 19 .
22. A high gradient insulator (HGI) formed by the method of claim 20 .
23. A method of making a high gradient insulator (HGI), comprising:
pre-cutting individual layers of the HGI to their final dimensions;
stacking the individual pre-cut layers to form an assembly;
pressing the assembly into an HGI unit with the desired dimensions.
24. The method of claim 23 wherein the pre-cut individual layers are stacked in or around a sacrificial alignment tube to form the assembly, and further comprising removing the alignment tube after pressing the assembly.