First Name: J.
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Last Name: Lewellen
Full Name: J. Lewellen
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3 papers
| title: | Investigations of electron-beam microbunching and beam coalignment using CTR in a high-gain SASE FEL |
| format: | conference procceeding |
| conference: | 2001 Particle Accelerator Conference |
| year: | 2001 |
| 11 authors: | | | | | | | | | | | |
| abstract: | We recently extended our experiments on z-dependent electron-beam microbunching using coherent transition radiation (CTR) into the high-gain, self-amplified spontaneous emission free-electron laser (FEL) regime. The UV-visible FEL at the Advanced Photon Source was operated at 530 nm and 385 nm using the bunch-compressed photocathode gun electron beam, linac, and 21.6 m of undulator length. The longitudinal microbunching of the electron beam was tracked by inserting a metal foil and a mirror after each of the nine 2.4-m-long undulators. The visible CTR generated by the electron-beam interaction was imaged and analyzed for z-dependent intensity, angular distribution, and spot size. Additionally, the image centroids and structures were used in evaluating the critical electron beam/photon beam overlap issue as a complement to the trajectory data from the beam position monitors. (9 References). |
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| title: | High-Brightness Beam Generation and Characterization at the Advanced Photon Source Low-Energy Undulator Test Line Linac |
| format: | conference procceeding |
| conference: | APS April Meeting |
| year: | 2000 |
| 9 authors: | | | | | | | | | |
| abstract: | Improvements to the Advanced Photon Source injector linac have been made to allow for the production and characterization of high-brightness beams in support of fourth-generation light source research. In particular, effort has been directed at generating beams suitable for use in the low-energy undulator test line (LEUTL) free-electron laser (FEL). We describe the enhancements to the linac operational and diagnostic capabilities that enabled self-amplified spontaneous emission (SASE) operation of the FEL at 530 nm. Electron beam measurement techniques and recent results will be discussed. Beam properties are measured under the same operational conditions as those used for FEL studies. The nominal FEL beam parameters are as follows: 217 MeV beam energy; less than 0.15 mm-mrad normalized emittance; 100 A peak current from a 0.7-nC charge at a 7-psec bunch. |
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| title: | High-Brightness Beams from a Light Source Injector: The Advanced Photon Source Low-Energy Undulator Test Line Linac |
| format: | conference procceeding |
| conference: | 2000 Linear Accelerator Conference |
| year: | 2000 |
| 9 authors: | | | | | | | | | |
| abstract: | The use of existing linacs, and in particular light source injectors, for free-electron laser (FEL) experiments is becoming more common due to the desire to test FELs at ever shorter wavelengths. The high-brightness, highcurrent beams required by high gain FELs impose technical specifications that most existing linacs were not designed to meet. Moreover, the need for specialized diagnostics, especially shot-to-shot data acquisition, demands substantial modification and upgrade of conventional linacs. Improvements have been made to the Advanced Photon Source (APS) injector linac in order to produce and characterize high brightness beams. Specifically, effort has been directed at generating beams suitable for use in the low-energy undulator test line (LEUTL) FEL in support of fourth-generation light source research. The enhancements to the linac technical and diagnostic capabilities that allowed for self-amplified spontaneous emission (SASE) operation of the FEL at 530 nm are described. Recent results, including details on technical systems improvements and electron beam measurement techniques, will be discussed. The linac is capable of accelerating beams to over 650 MeV. The nominal FEL beam parameters used are as follows: 217 MeV energy; 0.1-0.2% rms energy spread; 4-8 um normalized rms emittance; 80-120 A peak current from a 0.2-0.7 nC charge at a 2-7 ps FWHM bunch. |
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