Non-disturbing measurements of hollow-anode plasma parameters

Thomson scattering and visible spectroscopy were applied to study the parameters of plasma formed in a hollow-anode discharge (about 1 kA) prior and during electron beam extraction (approximately 1 kA; 300 kV). The discharge was ignited and sustained by ferroelectric plasma sources incorporated in the hollow anode. It was found that during the hollow-anode operation the density and energy of the ferroelectric surface plasma electrons are about 1015 cm−3 and not more than 5 eV, respectively. The density and temperature of the bulk hollow anode plasma electrons were found to be about 6×1013 cm−3 and about 10 eV, respectively. During an acceleration pulse the surface plasma electron density and energy increased to approximately 6×1016 cm−3 and not more than 20 eV respectively, while the bulk plasma parameters remain unchanged. Also, it was shown that the plasma formation on the ferroelectric surface is accompanied by the generation of microparticles having velocities up to 3×105 cm s−1.