  Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond
electron bunch traveling along the axis of a hollow cylindrical
dielectric-lined waveguide. We present a scheme of compact THz radiation source
based on the photocathode rf gun. On the basis of our analytic result, the
subpicosecond electron bunch with high charge (800pC) can be generated directly
in the photocathode rf gun. A narrow emission spectrum peaked at 0.24 THz with
2 megawatt (MW) peak power is expected to gain in the proposed scheme (the
length of the facility is about 1.2 m), according to the analytical and
simulated results.
