[en] The paper presents modified cathode assemblies, including their main characteristics, for plasma electron sources based on a constricted low-pressure arc initiated by a discharge in crossed electric and magnetic fields. One of the modified cathode assemblies allows the electrode system of the auxiliary discharge to operate at a pressure of ≈ 0.3 Pa, as against ≈ 10 Pa before the modification, provides a larger diameter constriction of the pulsed (up to τ = 250 μs) arc, and thus extends the range of operating currents for the plasma-cathode discharge system up to I_d = 300 A. The other modified assembly operates at widely varying discharge currents I_d = 5-100 A, provides lesser amounts of cathode microdroplets at the discharge electrodes, and allows the arc to operate at comparatively low voltages. The use of cathode assemblies adapted for specific discharge systems extends the capabilities of plasma- emitter electron sources as well as the range of their applications in scientific and technological fields. (paper)