Superstructure for high current applications in superconducting linear accelerators

1. A superstructure for accelerating charged particles in a high energy particle beam comprising:

two coupled multi-cell accelerating subunits;

said subunits including an entrance opening, an exit opening, and a beam line therebetween;

a beam pipe connecting said subunits;

a higher order mode coupler at said entrance and said exit of each of said subunits;

a power coupling device for feeding rf power into said subunits;

said subunits and beam pipe maintained at cryogenic temperature; and

said beam pipe between said subunits of a length selected to provide synchronism between particles and rf fields in both subunits.

2. The super-structure of claim 1 wherein each of said multi-cell subunits include between one and nine cells.

3. The super-structure of claim 1 including

a first and a second subunit;

two of said higher order mode couplers at said entrance opening of said first subunit;

two of said higher order mode couplers at said exit opening of said second subunit; and

two of said higher order mode couplers at said beam pipe.

4. The super-structure of claim 1 wherein said subunits and said beam pipe are maintained at a temperature below 4.2 K.

5. The super-structure of claim 4 wherein said length of said beam pipe between said subunits is equal to one-half of the wavelength.

6. The super-structure of claim 2 wherein said cells include

an equator having a diameter;

a center iris having a diameter; and

a cell length.

7. The super-structure of claim 1 wherein said higher order mode coupler is of the coaxial type.

8. The super-structure of claim 1 wherein said power coupling device is of the coaxial type.

9. The super-structure of claim 1 wherein said subunits and said beam pipe are constructed of niobium.

10. A superstructure for accelerating charged particles in a high energy particle beam comprising:

a first multi-cell accelerating subunit;

a second multi-cell accelerating subunit coupled to said first subunit;

said subunits including an entrance opening, an exit opening, and a beam line therebetween;

a beam pipe connecting said first and second subunit;

a higher order mode coupler at

said entrance opening of said first subunit;

said exit opening of said second subunit; and

at said beam pipe;

a power coupling device for feeding rf power into said subunits;

said subunits and beam pipe maintained at cryogenic temperature; and

said beam pipe between said subunits of a length selected to provide synchronism between particles and rf fields in both subunits.

11. The super-structure of claim 10 wherein each of said multi-cell subunits include between one and nine cells.

12. The super-structure of claim 10 wherein said higher order mode coupler is of the coaxial type.

13. The super-structure of claim 10 wherein said power coupling device is of the coaxial type.

14. The super-structure of claim 10 wherein said higher order mode coupler includes two separate couplers.

15. A method for developing a superstructure for accelerating charged particles in a high energy particle beam including

selecting a resonant frequency;

providing a cell including a cell length, an equator diameter, and an iris diameter;

connecting a plurality of the cells into a multi-cell subunit;

connecting the subunits with a beam tube;

coupling the subunits;

providing a plurality of couplers for feeding rf power into the subunits to define a superstructure;

identifying the monopole modes for the superstructure;

adjusting the field strength of each monopole mode to achieve appropriate damping;

determining the dipole modes at a range of frequencies, and

verifying that the impedances for each dipole mode.

16. The method of claim 15 wherein said multi-cell subunit includes between one and nine cells.