The photon emission accompanying fracture of a polycrystalline MgO was investigated at
room temperature under N2 gas pressures from 10-4 to 105 Pa. At fracture, the ultraviolet, visible and
infrared photon emissions instantaneously increased, and then rapidly decreased in most of the
experimental conditions. However, in a N2 gas pressure of around 100 Pa, their peak counts lasted for
about 10 milliseconds, and the amount of the UV photon emission was fifteen times larger than those
obtained in the other N2 gas pressures. This abrupt increment in the emission was explained by the
luminescence due to N2 gas discharge according to the classical Townsend’s theory. In conclusion,
the photon emission accompanying fracture of a polycrystalline MgO mainly originated from the
excited defects as reported by the authors previously, but the N2 gas discharge had a supplementary
effect on the emission around a specific N2 gas pressure.
Improvement of the hot-cathode gas discharge tube
