Conceptual design of a novel instrument far producing intense pulses of 10 ps X-rays for ultra-fast fluorescence measurements

Abstract

We report a conceptual design of a novel bench-top device for producing intense, fast pulses of X-rays with 10 ps fwhm (full-width at half-maximum) 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 three sections: (1) an electron gun that generates 5 ns wide pulses of electrons; (2) solenoidal magnetic lenses and rectangular deflection plates that focus the electrons onto an aperture plate and sweep the pulsed beam past the slit aperture, respectively; and (3) a tungsten anode onto which the post-aperture electrons are focused, producing X-ray pulses. Solenoidal magnetic lenses with a current density of 150 A/spl middot/turns/cm/sup 2/ focus the 120 keV electron beam to a spot diameter of 0.32 mm such that a deflection plate dV/dt of 10/sup 13/ V/s (achieved with power triode circuitry) will yield X-ray pulse widths of about 10 ps. We used EGUN, an electron optics and gun design program, to simulate the electron trajectories throughout the instrument.