| Paper | Title | Page |
|---|---|---|
| TU6PFP100 | Temperature and Stress Rise Induced by Cracks in Accelerating Structures | 1529 |
|
||
|
Funding: Office of High Energy Physics of DoE. The achievable gradient of accelerating structures is limited by dark current capture, RF breakdown and cyclic fatigue. We consider only one effect related to the cyclic fatigue which can be important for reliable operation of high gradient structures, viz. the temperature and stress rise caused by the RF magnetic fields which can be increased in cracks. We made detailed analysis and simulations on the temperature and stress distribution and temporal evolution in the vicinity of cracks of different shapes on the copper when there is a heat flux, and compared the results to the case of a smooth metallic plane. We found out that the temperature will approximately double at the crack upper corners and stress will increase several times at the crack bottom at the beginning and then drop as the crack grows. This analysis gives some insight of the cyclic fatigue leading to the formation of microcracks and crack growth. |
||
| FR5PFP098 | Self-Consistent Non-Stationary Model for Multipactor Analysis in Dielectric-Loaded Accelerator Structures | 4532 |
|
||
|
Funding: Office of High Energy Physics, US Department of Energy (DoE). Multipactor (MP) may occur in many situations: one- and two-surface MP, resonant and poly-phase-MP, on the surface of metals and dielectrics etc. We consider this phenomenon in dielectric loaded accelerator (DLA) structures. The starting point for our work is experimental and theoretical studies of such structures jointly done by Argonne National Lab and Naval Research Lab*. In the theoretical model developed during those studies, the space charge field due to the accumulated charged particles is taken into account as a parameter. We offer a non-stationary 2D cylindrical model where the DC field is taken into account self-consistently. We have improved our previous model** and demonstrated that its predictions are in good agreement with the results of other studies***. We also demonstrate some recent results where the effects of axial particle motion are taken into account. *J.G. Power et al., PRL, 92, 164801, 2004 |