News and Announcements
Employment Opportunities and Position Announcements
Achievements and News Reports
August 29 , 2005: Duke Chemists Find Possible Reason Why Redheads Have More Skin Cancer Discovery made with "free-electron" laser and special microscope (Duke Dialogue).
August 16, 2005: First lasing of a circularly polarized optical klystron FEL at Duke
We are pleased to announce the first lasing of a new Duke FEL powered by two OK-5 wigglers in the optical klystron configuration. This new FEL produced 450 nm, circularly polarized coherent radiation for the first time at 19:58 EST, August 14, 2005. With this first lasing, the Duke FEL lab presently operates both the OK-4 FEL (linear polarization) and OK-5 FEL (circular polarization with two wigglers), as well as the infrared Mark III FEL.
Like the OK-4 FEL, the new optical klystron FEL is driven by the 0.27 - 1.2 GeV Duke storage ring. The length of the FEL cavity is 53.73 meters. The FEL is typically operated in one-bunch or two-bunch (separated by a half circumference) modes. This new FEL is powered by two OK-5 wigglers, electromagnetic wigglers with two sets of wiggler arrays which can be configured to produce either circular or linear polarizations. Each wiggler is 4 meters long with thirty-two (32) 12-cm periods.
For this 450 nm lasing, the OK-5 wigglers are configured to produce the circularly polarized light by driving both horizontal and vertical wiggler arrays in series. With fixed electron beam orbits in the OK-5 wigglers, the initial measurements show that the lasing threshold current was 3 mA/bunch at 350 MeV and the extracted power was about 8 mW (4 mW from each side of the optical cavity) at 14 mA of beam current at 400 MeV. Higher lasing power is expected with further tuning.
The FEL upgrade at Duke is being carried out in three phases. This new FEL is an intermediate phase of the OK-5 system, operating two wigglers. The third phase FEL upgrade will employ four OK-5 type wigglers to form a new distributed optical klystron FEL with variable polarizations.
The OK-5 FEL system is a joint research project between the Duke FEL lab (DFELL) and the Budker Institute of Nuclear Physics (BINP), Russia. We would like to take this moment to thank BINP colleagues for their key contribution to this successful first lasing. We also would like to thank US Air Force Office of Scientific Research (AFOSR)'s MFEL Program for funding this research project.
-- Y. K. Wu, on behalf of Duke FEL lab accelerator physics group
April 8, 2005: Online Cover for Physical Review Letters
Images of part of a cycle of "hollow" electron beam evolution in the Duke storage ring; the beam consists of a large outside ring and a small core beam. Initially there is a phase of slow migration from ring to core (images 1-5), followed by a rapid core burst when the charge in the core becomes unstable (6-8), after which the beam quickly returns to the initial configuration to start the cycle again. [Full text of paper]
January 15, 2005: Improvements at Free-Electron Laser Laboratory Will Enhance Research Improved lasers will help researchers study topics from black holes to nerve tissue scarring (Duke Dialogue).
March 28, 2003: Laser Micro-Scalpel Yields Biological Insights into Tissue Dynamics Understanding a seemingly arcane embryonic process in fruit flies could yield insights into wound-healing and spina bifida (Duke Dialogue).
Conference and Seminar Announcements
- Colloquia information can be found on the Duke Physics Department's
- Previous Events:
22nd Annual International Free Electron Laser Conference, August 2000