| Summary: | 碩士 === 國立清華大學 === 動力機械工程學系 === 93 === In order to supply synchrotron radiation of higher quality, a storage ring with a high frequency resonant cavity is necessary to accelerate the electron beam. In operating environment, the pressure and temperature difference may cause structural deformation in the cavity, which results in the instability of interior electron beam, the working frequency fluctuation and the degradation of light source quality. In this paper, the interior electromagnetic characteristics of a 1.5GHz pill-box resonant cavity is obtained using the ANSYS code by combining the structural and electromagnetic analyses. The results showed that the resonant frequency would fluctuate more severely for a cavity with bigger aperture and shorter wave-guide’s length. Under the condition of thermal contraction from room temperature to liquid Helium temperature and 1atm external pressure, the pill-box cavity would produce a tolerable 3MHz of frequency fluctuation.
The cryogenic characteristics of material properties were found based on the frequency drift in different environment temperature and loading. By the parametric study, the results show that the frequency increases for larger thermal contraction and external pressure; however, the frequency decreases for increasing Young’s modulus, Poison’s ratio and cavity thickness. Finally, the cryogenic material properties of an aluminum cavity were obtained by combing the above numerical procedure and experiment to measure the frequency drift for verification.
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