CONCEPTUAL DESIGN OF A NOVEL INSTRUMENT FOR PRODUCING INTENSE PULSES OF 10 PS X-RAYS FOR ULTRA-FAST FLUORESCENCE MEASUREMENTS

We report a conceptual design of a novel bench-top device for producin g intense, fast pulses of x-rays with 10 ps fwhm (full-width at half-m aximum) x-ray pulse width, 120 keV maximum energy, 100 kHz repetition rate, and 1 A peak current onto the x-ray anode. The device includes t hree sections: (1) an electron gun that generates 5 ns wide pulses of electrons; (2) solenoidal magnetic lenses and rectangular deflection p lates that focus the electrons onto an aperture plate and sweep the pu lsed beam past the slit aperture, respectively; and (3) a tungsten ano de onto which the post-aperture electrons are focused, producing x-ray pulses. Solenoidal magnetic lenses with a current density of 150 A.tu rns/cm(2) focus the 120 keV electron beam to a spot diameter of 0.32 m m such that a deflection plate dV/dt of 10(13) V/s (achieved with powe r triode circuitry) will yield x-ray pulse widths of about 10 ps. We u sed EGUN, an electron optics and gun design program, to simulate the e lectron trajectories throughout the instrument.