The ferroelectric plasma thruster

: The Ferroelectric Plasma Thruster (FEPT) has been developed as an electrostatic micropropulsion thruster for the smallest classes of spacecraft. The FEPT consists of a thin wafer of lithium niobate ferroelectric material, with a solid electrode on one side, and an electrode with an aperture on the other. When radiofrequency high voltage is applied between the electrodes, through the thickness of the crystal, a combination of triple point and piezoelectric effects produce dense plasma on the crystal surface. The ions from this plasma are accelerated by the applied field on the positive half cycle producing thrusts measured to be between 61 and 87 microNewtons, depending on applied voltage. Electrons are emitted during the negative half cycle, making the device potentially self-neutralizing. The ion beam consisted of silver ions applied to the crystal surface and crystal materials. Ion energies were measured to be about 97 eV with 12 nC in each ion pulse. The specific impulse was measured to be between 183-587 5, with some neutral flow. Thrust efficiency was between 1-4%, with power input between 4 and 20 W.