CYCLOTRONS 2010 - List of Authors (Humbel, J.M.)

Paper

Title

Page

Towards Quantitative Predictions of High Power Cyclotrons

144

Y.J. Bi, J.J. Yang, T.J. Zhang
CIAE, Beijing, People's Republic of China
A. Adelmann, R. Dölling, J.M. Humbel, W. Joho, M. Seidel
PSI, Villigen, Switzerland
Y.J. Bi
Tsinghua University, Beijing, People's Republic of China
C.-X. Tang
TUB, Beijing, People's Republic of China

The large and complex structure of cyclotrons poses great challenges in the precise simulation of high power beams. However, such simulation capabilities are mandatory in the design and operation of the next generation high power proton drivers. The powerful tool OPAL enables us to do large scale simulations including 3D space charge and particle matter interactions. A large scale simulation effort is presented in the paper, which leads to a better quantitative understanding of the existing PSI high power proton cyclotron facility and predicts the beam behavior of CYCIAE-100 under construction at CIAE. The beam power of 1.3 MW delivered by the PSI 590 MeV Ring Cyclotron together with stringent requirements regarding the controlled and uncontrolled beam losses poses great challenges to predictive simulations. The comparisons with measurements show that OPAL can precisely predict the radial beam pattern at extraction with large dynamic range (3-4 orders of magnitude). The new particle matter interaction model is used to obtain necessary beam loss statistics during the acceleration. This data is indispensable in the design of an efficient collimation system in CYCIAE-100.

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]

Paper	Title	Page
MOPCP045	Towards Quantitative Predictions of High Power Cyclotrons	144
	Y.J. Bi, J.J. Yang, T.J. Zhang CIAE, Beijing, People's Republic of China A. Adelmann, R. Dölling, J.M. Humbel, W. Joho, M. Seidel PSI, Villigen, Switzerland Y.J. Bi Tsinghua University, Beijing, People's Republic of China C.-X. Tang TUB, Beijing, People's Republic of China
	The large and complex structure of cyclotrons poses great challenges in the precise simulation of high power beams. However, such simulation capabilities are mandatory in the design and operation of the next generation high power proton drivers. The powerful tool OPAL enables us to do large scale simulations including 3D space charge and particle matter interactions. A large scale simulation effort is presented in the paper, which leads to a better quantitative understanding of the existing PSI high power proton cyclotron facility and predicts the beam behavior of CYCIAE-100 under construction at CIAE. The beam power of 1.3 MW delivered by the PSI 590 MeV Ring Cyclotron together with stringent requirements regarding the controlled and uncontrolled beam losses poses great challenges to predictive simulations. The comparisons with measurements show that OPAL can precisely predict the radial beam pattern at extraction with large dynamic range (3-4 orders of magnitude). The new particle matter interaction model is used to obtain necessary beam loss statistics during the acceleration. This data is indispensable in the design of an efficient collimation system in CYCIAE-100.

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]