Initial testing of a field symmetrized dual feed 2 MeV 17 GHz RF gun

A 3 cell 17.14 GHz RF gun designed and built by Haimson Research Corporation (HRC) [J. Haimson, B. Meckleburg, and G. Stowell, "A field symmetrized dual feed 2 MeV RF gun for a 17 GHz electron linear accelerator", Advanced Accelerator Concepts, AIP Conference Proceedings, vol. 472, pp. 653-667, 1998] is being tested at the Plasma-Science and Fusion Center at MIT. The middle cavity consists of a racetrack design having dual-feed coupling holes for achieving highly symmetrical TM₀₁ π-mode operation. The high symmetry is important for reducing the beam emittance. The power into the RF gun is supplied by an HRC 25 MW, 17 GHz relativistic klystron amplifier. A 1 MW, 100 ns input pulse is required to achieve a peak axial electric field of 150 MV/m in the cavities to provide the electron-bunch with a 1.6 MeV energy gain. A 2 ps, 20 μJ laser pulse is injected into the back of the first cell for emitting the electron bunch. The diagnostic setup consists of a YAG screen and a CCD camera for beam imaging, and a slit array, a magnetic spectrometer, and a Faraday Cup for emittance, energy, and bunch charge measurements, respectively. The RF gun is currently being fed by ∼ 0.7 MW, 100 ns pulses. Our next goals are to process the gun up to 1 MW and 100 ns pulses, to inject the laser pulse and synchronize it with the RF phase, and to measure the output bunch energy, brightness, and duration. The status of the experimental results is presented.