To find a new light source

especially short-wave coherent light source has been to strive goal of the people.A combination between crystalline Undulator field with the klystron technology is expected to be short-wave coherent light source

in particular the coherent

-light source.In the paper discussed the possibility of a periodic bent crystal as

-klystron by Lasing effect of the periodic bent crystal.In the framework of classical mechanics and the small gain approximation

the longitudinal motion equation of the particles in the crystalline Undulator is reduced into classical pendulum equation

and derived the energy gain of the system by perturbated method.The results show that when the bent crystal worked in the amplifier mode

th

e required beam intensity is more high.If the bent crystal worked in the cascading klystron mode

the requirements of beam intensity can be reduced by 3-4 orders of magnitude

entirely lie within the capabilities of today's accelerator technology.