STATUS OF BEAM TESTING

current

Work has been temporarily suspended since September, 1997 pending procurement of additional funding.

14-Aug-97

The longest beam pulse remains at 5 milliseconds at 2 Amps, recirculation is 99.97 % (note that this is greater than the 99.92 % required for DC operation). The project remains in phase 2 configuration.

Currently pulse length is limited by a collector beam optics problem. Construction of the full collector power supply was deferred until installation of the FEL introduced energy spread to the beam. A temporary 800 V supply was installed capable of supplying 2 Amps current to one upper stage. The other stages were powered from taps on the gun cathode supply which has only milliamp current capability.
[beam trajectories as designed][gif 12K] The collector beam optics as designed are shown here.
beam trajectories w/800 V supply]

The optics with the 800 V temporary supply are shown here. It is now realized that an excessive number of electrons are turning around and being captured at lower stages, exceeding their current capacity, and thus imposing the 5 ms limit.
[gif 8K]


[beam trajectories w/2 KV supply][gif 7K] Beam optics with a new temporary supply operated at 2 KV are shown here. This configuration should force all electrons to the backside of the intended collection electrode.
[photo of new temporary collector power supply]

The new temporary collector power supply is capable of providing up to 3 KV at 2 Amps.
[gif 102K][jpeg 33K]