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td>VISA is a Free Electron Laser (FEL) experiment to study the
physics of Self Amplified Stimulated Emission (SASE). The experiment is carried out at the
Accelerator Test Facility (ATF),
part of the Brookhaven National Laboratory (BNL). Intense electron bunches produced by the
ATF photoinjector and accelerated by the ATF linac to energies of about 71 MeV pass
through the 4-m-long VISA undulator to p
roduce intense pulses of light in the infrared to
visible wavelength regime. The study includes the areas of radiation startup from noise,
the FEL collective instability regime and staturation as well as the temporal, spectral
and angular characteristics of the radiation. An extensive set diagnostics tools is used
to allow a detailed comparison of the experimental results with the theory and to
benchmark the simulation codes. The experiment is being conducted by the VISA group, a
collaboration of several laboratories and institutions in the United State, including the Brookhaven National Laboratory (BNL), the Livermore National Laboratory (LLNL), the Stanford Linear Accelerator Center (SLAC) and the University of California at Los Angeles (UCLA).
It is part the Linac C
oherent Light
Source (LCLS) R&D program to demonstrate the feasibility of X-ray FELs based on
the SASE collective instability regime.
