H. Ishizuka (a), Y. Kawamura (a), K. Yokoo (b), H. Shimawaki (b), A. Hosono (c)
(a) Fukuoka Institute of Technology, (b) Tohoku University, (c) Mitsubishi Electric Corporation
Smith-Purcell (SP) radiation at wavelengths of 350-750 nm was produced in a tabletop experiment using a field-emitter array (FEA) cathode. The electron gun was 5 cm long, and a 25 mm x 25 mm holographic replica grating was placed behind the slit provided in the anode. A regulated dc power supply generated a > 10 microampere electron beam of up to 45 keV while a small feedback-stabilized Van de Graaff generator accelerated lower currents to higher energies. The grating had a 0.556 micron period, 30 degree blaze and a 0.2 micron thick aluminum coating. Spectral characteristics of the radiation were measured automatically; the spectrometer was driven by a stepping motor to scan the wavelength and ad-converted signals from a photomultiplier tube were processed by a personal computer. The measurements, made at 80 degrees relative to the electron beam, showed good agreement with predicted wavelengths of the SP radiation. Diffraction orders of the detected radiation were -2 and -3 for beam energies higher than 45 keV, -4 and -5 around 20 keV, and -2 to -4 in between. We may conclude that practical applicability of FEAs to a compact radiation source was verified by this experiment.
