Electric propulsion system including heaterless dispenser cathode

A circuit for igniting and sustaining an electron discharge, comprising:

• an ignitor circuit including:
• a voltage transformer which is an in-phase transformer that includes a primary and a secondary, the primary including a first dot terminal and a first non-dot terminal, and the secondary including a second dot terminal and a second non-dot terminal;
• a reset circuit connected in parallel to the primary of the voltage transformer, and configured to provide a flux reset to a core of the transformer;
• a first rectifier connected in series between the second dot terminal of the secondary of the voltage transformer and a first node, the first node connecting an output of the first rectifier to a keeper;
• the second non-dot terminal of the secondary of the voltage transformer connected to a dispenser cathode via a second node that is different than the first node;
• and
• a sustaining circuit including:
• a current source having a return connected to the second node;
• and
• a second rectifier connected in series between the current source and the first node;
• and
• a DC load that is separate from the current source, that connects an input of the second rectifier to the second node, and that has a voltage that is higher than a voltage of the dispenser cathode.