| Paper | Title | Page |
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| TUP044 | Shunt Impedance Measurement of the APS BBC Gun | 346 |
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| The Advanced Photon Source (APS) ballistic bunch compression (BBC) injector is presently in use as a beam source for a number of experiments, including THz generation, beam position monitor testing for the Linac Coherent Light Source (LCLS), novel cathode testing, and radiation therapy source development. The APS BBC gun uses three independently powered and phased rf cavities, one cathode cell and two full cells, to provide beam energies from 2 – 10 MeV with variable energy spread, energy chirp, and, to an extent, bunch duration. The shunt impedance of an rf accelerator determines how effectively the accelerator can convert supplied rf power to accelerating gradient. The calculation of the shunt impedance can be complicated if the beam energy changes substantially during its transit through a cavity, such as in a cathode cell. We present the results of direct measurements of the shunt impedance of the APS BBC gun on an individual cavity basis, including the cathode cell, as well as report on achieved gradients. We also present a comparison of the measured shunt impedance with theoretical values calculated from the rf models of the cavities. | ||
| TUP045 | Photothermal Cathode Measurements at the Advanced Photon Source | 349 |
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| The Advanced Photon Source (APS) ballistic bunch compression (BBC) injector presently uses an M-type thermionic dispenser cathode as a photocathode. This “photothermal” cathode offers substantial advantages over conventional metal photocathodes, including easy replacement and easy cleaning via the cathode’s built-in heater. We present the results of quantum efficiency measurements as a function of cathode heater power, laser pulse energy, and applied rf field strength. | ||
| TUP059 | Photoinjector Production of a Flat Beam with Transverse Emittance Ratio of 100 | 382 |
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The generation of a flat electron beam directly from a photoinjector is an attractive alternative to the electron damping ring as envisioned for linear colliders. It also has potential applications to light sources such as the generation of ultrashort x-ray pulses or Smith-Purcell free electron lasers. In this paper, we report on the experimental generation of a flat beam with a measured transverse emittance ratio of 100±20 for a bunch charge of ≅0.5~nC*. The experimental data, obtained at the Fermilab/NICADD Photoinjector Laboratory, are compared with numerical simulations and the expected scaling laws. Possible improvement of the experiment along with application for such a flat beams are discussed
* P. Piot, Y.-E. Sun and K.-J. Kim, Phys. Rev. ST Accel. Beams 9, 031001 (2006) |