Status report on the LACARA experiment

LACARA (Laser cyclotron auto-resonance accelerator) is an 'advanced concept' vacuum laser accelerator of electrons that is in the design and construction phase at the Accelerator Test Facility at Brookhaven National Laboratory. As a bunch moves along a solenoidal magnetic field (similar to6T), it is to be accelerated from 50MeV to similar to100MeV by interacting with a 0.8TW Gaussian-mode optical beam provided by a CO2 10.6mum laser system. We present a system design here for the electron as well as the laser optics to accomplish this objective. The laser optics must handle 5J and be capable of forming a Gaussian beam inside the solenoid with a 1.3mm waist and a Rayleigh Range of 50cm, followed by a dump. The electron optics will transport a bunch having input emittance of 0.015mm-mrad and 100mum waist through the magnet. Emittance- filtering may be necessary to yield an accelerated bunch having narrow energy-spread. The design presented shows that a useful test of this concept may be done in a way taking into account the specific features and requirements of the ATF facility. It is expected that the experiment will be assembled by October- November 2002.