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| TUPPP01 | DEE Voltage Calibration for the ACCEL Proton Therapy Cyclotron | electron, proton, vacuum, extraction | 102 | ||
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ACCEL Instruments GmbH has developed a superconducting cyclotron for the use in proton therapy systems. An essential step during the commissioning of the medical cyclotron is the calibration and balancing of the DEE voltages. Using a very compact and low cost X-ray detector the bremsstrahlung spectrum of stray electrons accelerated by the four RF cavities has been measured. To determine the peak voltage a regression analysis of the measured spectrum has been carried out using a non-linear multiple convolution model taking into account the energy gain of the stray electrons between the liner and the DEE, the bremsstrahlung spectrum integrated over angle as well as the attenuation effects caused by the liner and the limited detector resolution. The correlation between the model and the measurement was very good. A software tool enabling automatic spectrum acquisition and analysis capable of online determination of the DEE voltages has been developed in LabVIEW graphical programming environment. Careful balancing of the DEE voltages resulted in better beam focusing and a cyclotron extraction efficiency larger than 80%. The absolute acceleration voltage has been confirmed by turn-separation measurements.
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| TUPPP16 | Integration of a Large-Scale Eigenmode Solver into the ANSYS(c) Workflow Environment | resonance, free-electron-laser, laser, electron | 122 | ||
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The numerical computation of eigenfrequencies and eigenmodal fields of large accelerator cavities, based on full-wave, three-dimensional models, has attracted considerable interest in the recent past. In particular, it is of vital interest to know the performance characteristics, such as resonance frequency, quality figures and the modal fields, respectively, of such devices prior to construction; given the fact that the physical fabrication of a cavity is expensive and time-consuming, a device that does not comply with its specifications can not be tolerated; a robust and reliable digital prototyping methodology is therefore essential. Furthermore, modern cavity designs typically exhibit delicate and detailed geometrical features that must be considered for obtaining accurate results. At PSI a three-dimensional finite-element code has been developed to compute eigenvalues and eigenfields of accelerator cavities (*). While this code has been validated versus experimentally measured cavity data, its usage has remained somewhat limited due to missing functionality to connect it to industrial grade modeling software. Such an interface would allow creating advanced CAD geometries, meshing them in ANSYS and eventually exporting and analyzing the design in femaxx. We have therefore developed pre- and postprocessing software which imports meshes generated in ANSYS for a femaxx run. A postprocessing step generates a result file than can be imported into ANSYS and further be analyzed there. Thereby, we have integrated femaXX into the ANSYS workflow such that detailed cavity designs leading to large meshes can be analyzed with femaXX, taking advantage of its capability to address very large eigenvalue problems. Additionally, we have added functionality for parallel visualization to femaxx. We present a practical application of the pre- and postprocessing codes and compare the results against experimental values, where available, and other numerical codes when the model has no
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* P. Arbenz, M. Becka, R. Geus, U. L. Hetmaniuk, and T. Mengotti, |
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