Sequentially pulsed traveling wave accelerator

• US 20070145916A1
• Filed: 10/24/2006
• Published: 06/28/2007
• Est. Priority Date: 01/15/2004
• Status: Active Grant

• Current Assignee: Lawrence Livermore National Security LLC (Government of the United States of America)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Nelson, Scott, Caporaso, George, Poole, Brian
• Granted Patent: US 7,576,499 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 9/02 Travelling-wave linear accelerators travelling-wave tubes H01J25/34

Abstract

A sequentially pulsed traveling wave compact accelerator having two or more pulse forming lines each with a switch for producing a short acceleration pulse along a short length of a beam tube, and a trigger mechanism for sequentially triggering the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to the particle beam.

Claims

1. A short pulse dielectric wall accelerator comprising:

a dielectric beam tube of length L surrounding an acceleration axis;

at least two pulse-forming lines transversely connected to the beam tube, each pulse-forming line having a switch connectable to a high voltage potential for propagating at least one electrical wavefront(s) therethrough independent of other pulse-forming lines to produce a short acceleration pulse of pulse width τ

along a corresponding short axial length δ

L of the beam tube; and

means for sequentially controlling the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to said particles.

2. The short pulse dielectric wall accelerator of claim 1,

wherein each pulse-forming line is a Blumlein module comprising:

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

a second conductor adjacent to the first conductor, said second conductor having a first end switchable to the high voltage potential, and a second end adjacent the acceleration axis;

a third conductor adjacent to the second conductor, said third conductor having a first end, and a second end adjacent the acceleration axis;

a first dielectric material with a first dielectric constant that fills the space between the first and second conductors; and

a second dielectric material with a second dielectric constant that fills the space between the second and third conductors.

3. The short pulse dielectric wall accelerator of claim 2,

wherein the first, second, and third conductors and the first and second dielectric materials have parallel plate strip configurations extending from the first to second ends.

4. The short pulse dielectric wall accelerator of claim 2,

wherein the dielectric beam tube has a dielectric constant greater than the first and second dielectric materials.

5. The short pulse dielectric wall accelerator of claim 4,

wherein the dielectric beam tube comprises alternating layers of conductors and dielectrics in planes orthogonal to the acceleration axis.

6. The short pulse dielectric wall accelerator of claim 1,

wherein the means for sequentially controlling the switches is capable of simultaneously switching at least two adjacent pulse-forming lines forming a block and sequentially switching adjacent blocks, so that an acceleration pulse is sequentially formed through each block.

7. The short pulse dielectric wall accelerator of claim 1,

wherein the diameter d and length L of the beam tube satisfy the criteria L>

4d, so as to reduce fringe fields at the input and output ends of the dielectric beam tube.

8. The short pulse dielectric wall accelerator of claim 1, wherein the beam tube satisfies the criteria:

γ

τ

ν

>

d/0.6, where v is the velocity of the wave on the beam tube wall, d is the diameter of the beam tube, τ

is the pulse width where

9. A sequentially pulsed traveling wave linear accelerator comprising:

a plurality of pulse-forming lines extending to a transverse acceleration axis, each pulse-forming line having a switch connectable to a high voltage potential for propagating at least one electrical wavefront(s) therethrough independent of other pulse-forming lines to produce a short acceleration pulse adjacent a corresponding short axial length of the acceleration axis; and

a trigger operably connected to sequentially control the switches so that a traveling axial electric field is produced along the acceleration axis in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to said particles.

10. The sequentially pulsed traveling wave linear accelerator of claim 9,

wherein each pulse-forming line is a Blumlein module comprising:

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

a second conductor adjacent to the first conductor, said second conductor having a first end switchable to the high voltage potential, and a second end adjacent the acceleration axis;

a third conductor adjacent to the second conductor, said third conductor having a first end, and a second end adjacent the acceleration axis;

a first dielectric material with a first dielectric constant that fills the space between the first and second conductors; and

a second dielectric material with a second dielectric constant that fills the space between the second and third conductors.

11. The sequentially pulsed traveling wave linear accelerator of claim 10,

wherein the first, second, and third conductors and the first and second dielectric materials have parallel-plate strip configurations extending from the first to second ends.

12. The sequentially pulsed traveling wave linear accelerator of claim 9,

wherein the means for sequentially controlling the switches is capable of simultaneously switching at least two adjacent pulse-forming lines forming a block and sequentially switching adjacent blocks, so that an acceleration pulse is sequentially formed through each block.

13. A sequentially pulsed traveling wave linear accelerator comprising:

a dielectric beam tube of length L surrounding an acceleration axis;

at least two Blumlein modules, each forming a pulse-forming line transverse to the acceleration axis and comprising;

a first conductor having a first end, and a second end connected to the beam tube;

a second conductor adjacent to the first conductor, said second conductor having a first end switchable to the high voltage potential, and a second end connected to the beam tube;

a third conductor adjacent to the second conductor, said third conductor having a first end, and a second end connected to the beam tube;

a first dielectric material with a first dielectric constant that fills the space between the first and second conductors; and

a second dielectric material with a second dielectric constant that fills the space between the second and third conductors, with the first and second dielectric constants less than the dielectric constant of the beam tube;

each Blumlein module having at least one switch connectable to a high voltage potential for propagating at least one electrical wavefront(s) therethrough independent of other Blumlein modules to produce a short acceleration pulse of pulse width τ

along a corresponding short axial length δ

L of the beam tube; and

a controller operably connected to sequentially trigger the switches so that a traveling axial electric field is produced along the beam tube in synchronism with an axially traversing pulsed beam of charged particles to serially impart energy to said particles.

14. The sequentially pulsed traveling wave linear accelerator of claim 13,

wherein the Blumlein modules are symmetric Blumleins with the first and second dielectric constants equal.

15. The sequentially pulsed traveling wave linear accelerator of claim 13,

wherein the Blumlein modules are asymmetric Blumleins with the first and second dielectric constant unequal.