arXiv subjects

P. B. Wilson

Publications and source records attributed to P. B. Wilson.

3 recordsLinked to original sources

arXiv2002

Impedance Measurement Setup for Higher-Order Mode Studies in NLC Accelerator Structures with the Wire Method

Dipole modes are the main cause of transverse emittance dilution in the Japanese Linear Collider / Next Linear Collider (JLC/NLC). A diagnostic setup has been built in order to investigate them. The method is based on using a coaxial wire to excite and measure electromagnetic modes of accelerating structures. This method can offer a more efficient and less expensive procedure than the ASSET facility. Initial measurements have been made and are presented in this paper.

physics.acc-ph↗

arXiv2002

Tuning And Field Sensitivity Of Pi-Mode Standing Wave Linacs For The NLC

In order to mitigate the effects of electrical breakdown (which have been found to occur in SLAC X-band traveling wave structures) standing wave structures are being considered for the NLC linac. At SLAC, structures consisting of 15 cells operating in the p accelerating mode are being tested for their electrical breakdown characteristics. In this paper the tuning requirement on the cavities is elucidated by utilizing a circuit model of the structure. The sensitivity of the field to both random and systematic errors is also discussed.

physics.acc-ph↗

arXiv2000

A Plasma Model for RF Breakdown in Accelerator Structures

A plasma model is presented for the formation of ``cathode spots'' and subsequent crater development near field emission sites on a copper surface in the presence of a strong dc electric field. Adding to previously published models, we propose that the two-stream plasma instability relates the plasma density to its dimensions. Arguments are presented that suggest that the formation and dynamics of such plasma spots are essentially the same phenomenon for both dc and rf fields. A consequence for accelerating structures is that, when such plasma spots are present, they erode the copper surface at a rate on the order of 300 micrograms per Coulomb of ion bombardment current. This erosion rate can have a measurable effect on the rf properties of an accelerating structure after processing at high gradients for a few hundred hours.

physics.acc-ph↗