# US 10,485,090 B2 · High performance SRF accelerator structure and method

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- Number: US 10,485,090 B2
- Document ID: US10485090B2
- Status: Granted
- Kind: B2
- Application number: 15/411,986
- Filed: 2017-01-21
- Published: 2017-07-27
- Granted: 2019-11-19
- Earliest claimed: 2016-01-22
- Assignees: Jefferson Science Associates, LLC
- Applicants: Jefferson Science Associates, LLC
- Inventors: Ganapati Rao Myneni
- Web page: https://patentgrep.com/patent/US10485090B2

## CPC

- H05H 7/20: with superconductive walls
- H05H: PLASMA TECHNIQUE (apparatus or processes specially adapted for producing X-rays H05G2/00); PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS

## Abstract

A high performance accelerator structure and method of production. The method includes precision machining the inner surfaces of a pair of half-cells that are maintained in an inert atmosphere and at a temperature of 100 K or less. The method includes removing thin layers of the inner surfaces of the half-cells after which the roughness of the inner surfaces in measured with a profilimeter. Additional thin layers are removed until the inner surfaces of the half-cell measure less than 2 nm root mean square (RMS) roughness over a 1 mm2 area on the profilimeter. The two half-cells are welded together in an inert atmosphere to form an SRF cavity. The resultant SRF cavity includes a high accelerating gradient (Eacc) and a high quality factor (Q0).

## Claims

### Claim 1

A chemical rinse-free method of forming a superconducting radio frequency (SRF) accelerator cavity, comprising:
(a) providing a first and second half-cell of an accelerator cavity having an inner surface and an equator;
(b) adjusting the temperature of the first and second half-cell to 100 K or less;
(c) removing a thin layer of the inner surface of the first and second half-cell while holding the temperature of the first and second half-cell to 100K or less and maintaining the first and second half-cell in a first inert atmosphere;
(d) measuring the roughness of the inner surface of the first and second half-cell with a surface profilimeter;
(e) repeating steps (c) through (d) until the inner surface of the first and second half-cell is less than 2 nm root mean square (RMS) roughness over a 1 mm2 area; and
(f) welding the two half-cells together in a second inert atmosphere to form a superconducting radio frequency accelerator cavity.

### Claim 2 (depends on 1)

The method of claim 1 wherein said half-cells are constructed of niobium.

### Claim 3 (depends on 1)

The method of claim 1 wherein said half-cells are constructed of material selected from the group consisting of niobium, copper, vanadium, titanium, technetium, steel, and alloys thereof.

### Claim 4 (depends on 1)

The method of claim 1 wherein the accelerator cavity further comprises a quality factor (Q0) of 4×1010 or greater.

### Claim 5 (depends on 1)

The method of claim 1 wherein the accelerator cavity further comprises an accelerating gradient (Eacc) of 45 MV/m or greater.

### Claim 6 (depends on 1)

The method of claim 1 wherein the thin layer of the inner surface of the first and second half-cell is removed on a 3D milling machine.

### Claim 7 (depends on 1)

The method of claim 1 wherein the second inert atmosphere is selected from the group comprised of argon (Ar), helium (He), neon (Ne), krypton (Kr), and xenon (Xe).