Ultra high Q superconductive cavity resonator made of niobium having a limited number of crystal grains
A superconductive linear microwave particle accelerator is disclosed. The accelerator employs a coupled cavity accelerating structure arranged along a beam path for electromagnetic interaction with a beam of charged particles for accelerating the particles to nearly the velocity of light at the downstream end of the accelerator. The coupled cavity accelerator section comprises a plurality of coupled superconductive cavities made of niobium. The walls of the cavity resonators, which define the microwave current supporting surfaces of the cavities, are constituted of pure niobium having less than 20 crystallites of niobium per square inch as averaged over the entire current supportive surface of each cavity, whereby the radio frequency energy loss associated with the grain boundaries in the surface of the cavity is minimized in use. When there are less than 20 crystallites of niobium per square inch of the cavity surface, a Te/sub 0.1.1/ mode X-band niobium cavity will exhibit Q's in excess of 5 x 10/sup 9/ at temperatures of 1.2 to 1.3 degrees Kelvin and such high Q's have been measured for this mode and frequency. When an accelerator section is formed of cavities having less than 20 crystalites of niobium per square inch the Q of the coupled cavity accelerator section becomes extremely high at the operating temperatures of 1.2 to 1.3 degrees Kelvin, thereby greatly reducing the circuit energy losses caused by currents flowing in the accelerator walls and permitting relatively high current beams to be accelerated to nearly the velocity of light.
- Assignee:
- Varian Associates
- Patent Number(s):
- US 3493809
- OSTI ID:
- 7214672
- Resource Relation:
- Patent File Date: Filed date 21 Dec 1967
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
LINEAR ACCELERATORS
SUPERCONDUCTING CAVITY RESONATORS
FABRICATION
ANNEALING
GRAIN BOUNDARIES
GRAIN SIZE
NIOBIUM
QUALITY FACTOR
ACCELERATORS
CAVITY RESONATORS
CRYSTAL STRUCTURE
ELEMENTS
HEAT TREATMENTS
METALS
MICROSTRUCTURE
REFRACTORY METALS
SIZE
SUPERCONDUCTING DEVICES
TRANSITION ELEMENTS
430300* - Particle Accelerators- Auxiliaries & Components
420201 - Engineering- Cryogenic Equipment & Devices