Low-voltage high-curent field emission from a simple pointed graphite emitter tested in a transmission-type X-ray demonstator

We have fabricated pointed graphite emitters (PGEs) from a thin graphite foil by a rather simple cutting technique. After a sudden activation, PGEs reproducibly provide currents up to 3 mA at 4 V/μm, and after 2 h conditioning a nearly stable current of 500 μA over 10 h. Luminescent screen images reveal multiple field emitters from fluctuating spots. Such a PGE was used as reliable electron source in quatrode configuration for a transmission-type X-ray demonstrator. A first X-ray spectrum was obtained using a 5 μm thin Ni target.