http://swrc.ontoware.org/ontology#Thesis
Coherent Synchrotron Radiation and Microwave Instability in Electron Storage Rings
en
周 德民
ゾウ デミン
ZHOU Demin
総研大甲第1452号
This thesis work was dedicated to investigating coherent synchrotronradiation (CSR) and microwave instability (MWI) in electron rings.CSR is an important issue in modern electron/positron storage rings,where short bunch length and/or low emittance are usually desiredfor particle physics or to produce light.To better understand the physics of CSR, we developed a new code,CSRZ, for calculating CSR impedance for an arbitrarily curved chamber.The chamber has rectangular cross section. The CSR impedancecan be calculated with boundary conditions of perfectly conductingwalls or resistive walls. With low-level numerical noises and minimalnumerical damping, the code is well suitable for the task of calculatingCSR impedance in a series of bending magnets. With a tinyapproximation on the geometry of the chamber, which was assumedto be wiggling in the code, CSRZ can also be used to calculate thelongitudinal impedance due to coherent radiation in a wiggler (CWR).Therefore, CSRZ does ful_ll another mission of calculating the CWRimpedance in the wiggler sections of KEKB and SuperKEKB.An analytic eigenfunction expansion method was available to calculatethe longitudinal impedance due to CWR with rectangular chamber.The method used dyadic Green's functions in electromagnetic theoryand was rigorous for the case of straight chamber. Substantial alterationswere performed in order to make it applicable to calculatethe imaginary part of CWR impedance related to the beam self-_elds.Therefore we re-derived the theory and did _nd the full expressions forCWR impedance. With shielding of chamber, the CWR impedanceindicates resonant properties which were not seen in the theory forCWR in free space. The analytic work also provides excellent benchmarkingto the CSRZ code.The last part of this thesis addresses microwave instability (MWI)in the KEKB low energy ring (LER) and the SuperKEKB positrondamping ring (DR). Code development for simulating MWI was discussed_rst. For the KEKB LER, the impedances of various components,including CSR, were collected and used to survey the MWI.The CSR instability in the SuperKEKB DR was studied using existingtheories of instability analysis.
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