  A compact Inverse Compton Light Source (ICLS) design is presented, with flux
and brilliance orders of magnitude beyond conventional laboratory-scale sources
and other compact ICLS designs. This design utilizes the physics of inverse
Compton scattering of an extremely low emittance electron beam by a laser pulse
of rms length of approximately two-thirds of a picosecond (2/3 ps). The
accelerator is composed of a superconducting radiofrequency (SRF) reentrant gun
followed by four double-spoke SRF cavities. After the linac are three
quadrupole magnets to focus the electron beam to the interaction point (IP).
The distance from cathode surface to IP is less than 6 meters, with the cathode
producing electron bunches with a bunch charge of 10 pC and a few picoseconds
in length. The incident laser has 1 MW circulating power, a 1 micron
wavelength, and a spot size of 3.2 microns at the IP. The repetition rate of
this source is 100 MHz, in order to achieve a high flux despite the low bunch
charge. The anticipated X-ray source parameters include an energy of 12 keV,
with a total flux of $1.4\times10^{14}$ ph/s, the flux into a 0.1% bandwidth of
$2.1\times10^{11}$ ph/(s-0.1%BW), and the average brilliance of
$2.2\times10^{15}$ ph/(s-mm$^2$-mrad$^2$-0.1%BW).
