Cast dielectric composite linear accelerator

• US 20070138980A1
• Filed: 11/14/2006
• Published: 06/21/2007
• Est. Priority Date: 11/14/2005
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America), TPL Incorporated
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Sanders, David, Sampayan, Stephen, Slenes, Kirk, Stoller, H.M.
• Granted Patent: US 7,615,942 B2
• Time in Patent Office: Days
• US Class Current: 315/505
• CPC Class Codes: H05H 7/00 Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
• CPC Class Codes: H05H 7/22 Details of linear accelerators, e.g. drift tubes H05H7/02 - H05H7/20 take precedence
• CPC Class Codes: H05H 9/00 Linear accelerators

Abstract

A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

Claims

1. A compact linear accelerator comprising:

at least one transmission line(s) extending towards a transverse acceleration axis from a first end to a second end for propagating an electrical wavefront(s) therethrough to impress a pulsed gradient along the acceleration axis, each transmission line comprising;

a first conductor having first and second ends with the second end adjacent the acceleration axis;

a second conductor adjacent the first conductor and having first and second ends with the second end adjacent the acceleration axis; and

a cast dielectric composite that fills the space between the first and second conductors and comprising at least one organic polymer and at least one particle filler having a dielectric constant greater than that of the organic polymer.

2. The compact linear accelerator of claim 1,

wherein the first and second conductors and the cast dielectric composite have parallel-plate strip configurations extending longitudinally from the first to second ends.

3. The compact linear accelerator of claim 1,

wherein two transmission lines extend toward the transverse acceleration axis to form a Blumlein module comprising the first conductor, the second conductor, the dielectric composite therebetween, a third conductor adjacent the second conductor and having a first end and a second end adjacent the acceleration axis, and a second dielectric composite that fills the space between the second and third conductors and comprising at least one organic polymer and at least one particle filler having a dielectric constant greater than that of the organic polymer.

4. The compact linear accelerator of claim 3,

wherein the first and second dielectric composites have different dielectric constants to form an asymmetric Blumlein.

5. The compact linear accelerator of claim 3,

wherein the first and second dielectric composites have the same dielectric constants to form a symmetric Blumlein.

6. The compact linear accelerator of claim 3,

further comprising at least one additional Blumlein module stacked in alignment with the first Blumlein module.

7. The compact linear-accelerator of claim 1,

wherein the first and second conductors are coated with a material chosen from the group consisting of conductive, semi-conductive, semi-insulating, and insulating layers.

8. The compact linear accelerator of claim 1,

wherein the cast dielectric composite has a thickness greater than 0.005 inch.

9. The compact linear accelerator of claim 1,

wherein the cast dielectric composite has a dielectric constant from 2 to 40.

10. The compact linear accelerator of claim 1,

wherein the cast dielectric composite has a dielectric constant that varies less than 15% when the composite is subjected to a temperature of from −

55 to 125°

C.

11. The compact linear accelerator of claim 1,

wherein the cast dielectric composite has a breakdown voltage greater than 100 kV/cm.

12. The compact linear accelerator of claim 1,

wherein the at least one particle filler has a particle size substantially in the range between approximately 20 and 150 nanometers.

13. The compact linear accelerator of claim 12,

wherein the at least one particle filler comprises non-refractory ferroelectric particles having a cubic crystalline structure.

14. The compact linear accelerator of claim 13,

wherein the composite includes from about 10 to about 80 percent by weight ferroelectric particles.

15. The compact linear accelerator of claim 13,

wherein the ferroelectric particles are barium-based ceramic particles.

16. The compact linear accelerator of claim 13,

wherein the ferroelectric particles are selected from the group consisting of barium titanate, strontium titanate, and mixtures thereof.

17. A method of fabricating a linear accelerator, comprising:

casting at least one dielectric composite slab(s) comprising at least one organic polymer and at least one particle filler having a dielectric constant greater than that of the organic polymer;

coating the cast dielectric composite slab(s) with a second dielectric composite material having a dielectric constant greater than that of the cast dielectric slab(s); and

pressing two conductors against each second dielectric composite material-coated cast dielectric composite slab to extrude the second dielectric composite material out from therebetween to completely fill the triple point region with the second dielectric composite material.

18. The method of claim 17,

wherein at least two dielectric composite slabs are cast and coated with the second dielectric composite material, and at least three conductors are arranged and pressed in alternating layered arrangement with the second dielectric composite material-coated cast dielectric composite slabs.

19. The method of claim 18, wherein the second dielectric composite material further comprises a higher concentration of high dielectric constant nanoparticles.

20. A method of fabricating a linear accelerator, comprising:

positioning at least one conductor(s) in a mold cavity;

filling the mold cavity with a dielectric composite comprising at least one organic polymer(s) and at least one particle filler(s) space having a dielectric constant greater than that of the organic polymer(s), to at least partially immerse the conductor(s) in the composite; and

curing the dielectric composite to integrally cast the dielectric composite with the conductor(s).

21. The method of claim 20,

wherein at least two conductors are spaced from each other in the mold cavity to produce an alternating layered arrangement with the cast dielectric composite.