Ion engine grid arcing protection circuit

A grid arcing protection circuit for an ion thruster engine of a type that includes a pair of spaced-apart screen and accelerator grids disposed at different voltages and polarities, the circuit comprising:

• an impedance coupled in series between the accelerator grid and a current return path of the accelerator grid, the impedance being variable in response to an increase of current in the accelerator grid resulting from a plasma arc between the screen grid and the accelerator grid so as to decouple a substantial portion of the accelerator grid current from the return path and thereby rapidly reduce the voltage differential between the screen grid and the accelerator grid.

In an ion thruster engine of a type that includes a pair of spaced-apart screen and accelerator grids disposed at different voltages, a method for protecting the grids against damage caused by plasma arcing between the two grids, the method comprising:

• providing an impedance coupled in series between the accelerator grid and a current return path of the accelerator grid;
• and,
• converting an increase in current in the accelerator grid caused by a plasma arc between the screen grid and the accelerator grid into a reduction of the voltage differential between the screen grid and the accelerator grid with the impedance.

In an ion thruster engine of a type that includes a pair of spaced-apart screen and accelerator grids disposed at different voltages, a method for protecting the grids against damage caused by plasma arcing between the two grids, the method comprising:

• providing an impedance coupled in series between the accelerator grid and a current return path of the accelerator grid;
• and,
• varying the impedance in response to an increase of current in the accelerator grid resulting from a plasma arc between the screen grid and the accelerator grid to decouple a substantial portion of the accelerator grid current from the return path and thereby reduce the voltage differential between the screen grid and the accelerator grid.