  A device has been built and tested, in which a ceramic superconducting
cathode and a copper anode cause electrical discharges in low pressure gases,
at temperatures between 50 and 70 K. The electrodes are connected to a
capacitors array charged up to 2000 kV; peak currents are of the order of 10^4
A. The cathode has the diameter of 10 cm and is fabricated by OCMTG technology.
In discharges at voltage above 500 kV two new phenomena were observed, probably
related to each other. First, the discharge does not look like a spark, but is
a flat, glowing discharge, which originates from the whole surface of the
superconducting electrode. Furthermore, a radiation pulse is emitted at the
discharge, which propagates orthogonally to the cathode, towards the anode and
beyond it, in a collimated beam, apparently without any attenuation. The
radiation pulse carries an energy of 10^-3 J at least. The features and the
nature of this radiation have been investigated by several means, still it was
not possible to identify it; we can only exclude that it is electromagnetic
radiation or any other radiation with energy-momentum relationship E=cp.
