| Title |
Observation of Significant Quantum Efficiency Enhancement from a Polarized Photocathode with Distributed Brag Reflector |
| Authors |
- S. Zhang, M. Poelker, M.L. Stutzman
JLab, Newport News, Virginia, USA
- Y. Chen, A. Moy
SVT Associates, Eden Prairie, Minnesota, USA
|
| Abstract |
Polarized photocathodes with higher Quantum efficiency (QE) would help to reduce the technological challenge associated with producing polarized beams at milliampere levels, because less laser light would be required, which simplifies photocathode cooling requirements. And for a given amount of available laser power, higher QE would extend the photogun operating lifetime. The distributed Bragg reflector (DBR) concept was proposed to enhance the QE of strained-superlattice photocathodes by increasing the absorption of the incident photons using a Fabry-Perot cavity formed between the front surface of the photocathode and the substrate that includes a DBR, without compromising electron polarization. Here we present recent results showing QE enhancement of a GaAs/GaAsP strained-superlattice photocathode made with a DBR structure. Typically, a GaAs/GaAsP strained-superlattice photocathode without DBR provides a QE of 1%, at a laser wavelength corresponding to peak polarization. In comparison, the GaAs/GaAsP strained-superlattice photocathodes with DBR exhibited an enhancement of over 2 when the incident laser wavelength was tuned to meet the resonant condition for the Fabry-Perot resonator.
|
| Funding |
This project was supported by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177. |
| Paper |
download TUPMA038.PDF [0.770 MB / 3 pages] |
| Export |
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| Conference |
IPAC2015, Richmond, VA, USA |
| Series |
International Particle Accelerator Conference (6th) |
| Proceedings |
Link to full IPAC2015 Proccedings |
| Session |
Tuesday Posters (Madison) |
| Date |
05-May-15 16:00–18:00 |
| Main Classification |
2: Photon Sources and Electron Accelerators |
| Sub Classification |
T02 - Electron Sources |
| Keywords |
laser, polarization, electron, cathode, vacuum |
| Publisher |
JACoW, Geneva, Switzerland |
| Editors |
Stuart Henderson (ANL, Argonne, IL, USA); Evelyn Akers (Jlab, Newport News, VA, USA); Todd Satogata (JLab, Newport News, VA, USA); Volker R.W. Schaa (GSI, Darmstadt, Germany) |
| ISBN |
978-3-95450-168-7 |
| Published |
June 2015 |
| Copyright |
|
