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<b><font color="#000099">COLLOQUIUM
<br>
Wednesday, December 15, 2010<br>
CEBAF Center AUD. <br>
4pm with coffee and cookies at 3:45
<br>
<br>
"The Dawn of Higher Energy Photon Science at Jefferson Lab -
Initial
Lasing results from the UV Demo Free-Electron Laser"
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<br>
<b><font color="#cc0000">Michelle Shinn and Steve Benson
</font></b><br>
<br>
The Jefferson Lab FEL facility was always envisioned as having both
an
infrared and an ultraviolet (UV) free-electron laser. Recently we
have
completed the UV electron beam-line, installed the optics and
started
commissioning of the UVFEL operated at both a red wavelength and in
the
violet and ultraviolet region. This region is much more challenging
than the IR region due to a much greater sensitivity to the electron
beam quality and to mirror heating. We were therefore pleasantly
surprised to find that the lasing has been extremely robust, with
gains
of more than 100% per pass and an efficiency of almost 1%. Though
mirror heating is substantial, we have achieved over 100 Watts even
at
the ultraviolet wavelength of 370 nm and 200 W at 400 nm. We are
making
a concerted effort to try to match simulated results to the
experimental results and have found that reasonable agreement is
found
when three-dimensional guiding effects are included in the
simulations.
We now plan to operate with a hole output coupler that will allow us
to
push to much higher photon energies. These runs take advantage of
higher harmonic wavelengths naturally produced in the FEL. Initial
experiments are planned to use light with a photon energy of 10 eV.
In
this presentation we will discuss the experiments that motivated the
construction of this machine and outline some of the proposed
experiments in the vacuum ultraviolet.
<br>
<br>
This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150,
the Air Force Office of Scientific Research, DOE Basic Energy
Sciences,
the Office of Naval Research, and the Joint Technology Office.
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