Superconducting Cavity Beam Test in CESR
The first use of a superconducting accelerating structure in a storage ring is described. Two 5-cell 1500 MHz ''muffin tin'' superconducting niobium cavities (1 m active length) were operated in the Cornell 8 GeV e/sup +/e/sup -/ storage ring, CESR. A 6.1 mA beam was captured and stored at 3.5 GeV using only the superconducting cavity. Up to 12.5 kW was transferred to the beam by the cavity. Single bunch currents up to 12 mA were reached in conjunction with the normal 500 MHz RF. Beam induced higher order mode (HOM) powers of 290 W were carried to room-temperature loads by four couplers and waveguides; no HOM-induced cryogenic dissipation was detectable. Q's of the 76 most prominent resonances were measured. Transverse and longitudinal beam instabilities were studied by mechanically sweeping the tune of the cavities; current thresholds are compared to theory. The cavity exhibited the ability to survive breakdown at high incident power without degradation.
Impedance and Wakeeeld in a Superconducting Beam Pipe Impedance and Wakeeld in a Superconducting Beam Pipe
The impedance and the longitudinal wake eld in a superconducting beam pipe are derived. At low frequencies, this impedance is purely inductive, while at higher frequencies it approaches the resistive-wall impedance of a normal conductor. For very short bunches, the resistive heating of the beam pipe can induce quenches of the superconductor.
Titanium Vacuum Chamber Liners in the Cornell Electron Synchrotron
A method is described for constructing and installing solid metal liners inside epoxy filled synchrotron magnets.