CYCLOTRONS 2010 - List of Authors (Zhang, H.)

Paper

Title

Page

Disturbance Effects Caused by RF Power Leaking Out From Cavities in the PSI Ringcyclotron

341

J.M. Humbel
PSI-LRF, Villigen, PSI, Switzerland
H. Zhang
PSI, Villigen, Switzerland

While commissioning the PSI high intensity proton beam facility after the shutdown 2010 direct and indirect phenomena of interaction between the electrostatic septa of the injection and extraction region and the RF power, leaking out from the cavities occurred in the Ringcyclotron. As an indirect influence RF fields outside the cavities generate plasma clouds at the edge of magnet poles. Accelerated plasma ions sputtered metallic atoms form the vacuum chamber wall, which then covered the insulator surface with an electrically conductive layer. The septum therefore had to be replaced. Directly RF power, dissipated from the third harmonic cavity was redirected by a beam stopper in such a way, that a linear correlation between the RF pick up signal monitored at the extraction septum EEC and the leak current across the septum insulator could be observed. As an instant mending action the beam stopper, which is not permanently used, has been removed. The leaking out of RF power from a cavity is known to depend on vertical asymmetry. With asymmetrical settings of the hydraulic tuning system we will try to minimize this disturbing effect.

Slides WEM2CCO03 [3.166 MB]

Paper	Title	Page
WEM2CCO03	Disturbance Effects Caused by RF Power Leaking Out From Cavities in the PSI Ringcyclotron	341
	J.M. Humbel PSI-LRF, Villigen, PSI, Switzerland H. Zhang PSI, Villigen, Switzerland
	While commissioning the PSI high intensity proton beam facility after the shutdown 2010 direct and indirect phenomena of interaction between the electrostatic septa of the injection and extraction region and the RF power, leaking out from the cavities occurred in the Ringcyclotron. As an indirect influence RF fields outside the cavities generate plasma clouds at the edge of magnet poles. Accelerated plasma ions sputtered metallic atoms form the vacuum chamber wall, which then covered the insulator surface with an electrically conductive layer. The septum therefore had to be replaced. Directly RF power, dissipated from the third harmonic cavity was redirected by a beam stopper in such a way, that a linear correlation between the RF pick up signal monitored at the extraction septum EEC and the leak current across the septum insulator could be observed. As an instant mending action the beam stopper, which is not permanently used, has been removed. The leaking out of RF power from a cavity is known to depend on vertical asymmetry. With asymmetrical settings of the hydraulic tuning system we will try to minimize this disturbing effect.
	Slides WEM2CCO03 [3.166 MB]