Measurements of the radiation power of a high-current vacuum arc at high current densities

The radiation of a vacuum arc was measured in the spectral region 200nm ≤ λ ≤ 1100 nm. The arc was initiated in the center of the cathode by ignition discharge, by breaking the current in the auxiliary circuit, and was fed by the rectangular current pulse with a duration of 10 ms. The contact gap was fixed at 4mm, the butt D=30mm CuCr30 contacts were used. The arc was stabilized by an external uniform axial magnetic field. Radiation was removed through KU-1 quartz window of the vacuum chamber. The radiation detector was a silicon photodiode 1.2 mm in diameter located outside the vacuum chamber on an axis intersecting the axis of symmetry of the discharge at the center of the interelectrode gap. The signal from the photodiode was taken through an amplifier and recorded on an oscilloscope. The measurements were made in a range of currents from 10 kA to 25 kA, which corresponds to a mean current density in the developed discharge of 1.5 kA/cm
²
≤ j ≤ 3.5 kA/cm
²
. Considering the type of the spectral sensitivity of the diode, two series of measurements were made - measurements without a filter and through a ZhS-10 filter that cuts off radiation with λ ≤ 400nm. The results obtained made it possible to analyze the dependence of the radiation power on the arc current at different stages of the development of the arc. The results showed that at high current densities in the developed vacuum arc with anodic activity, a significant part of the power is transferred by radiation.