A laser and method of producing laser light. The laser and method involve passing
a high energy beam of particles through an evacuated chamber. A static electric
or magnetic field is established in the chamber in a direction that is essentially
perpendicular to the direction of propagation of the beam, but which is a periodically
varying field in the direction of propagation. The velocity of the particles and
the variation in the field is sufficient to pump the particles into a higher energy
state and produce laser light at the output of the chamber.
