Gasless sputtering: Opportunities for ultraclean metallization, coatings in space, and propulsion

Pulsed magnetron sputtering was demonstrated in high vacuum: no sputter gas was used at any time. Sustained selfsputtering was initiated by multiply charged ions from a short vacuum arc. Copper ion currents to an ion collector in excess of 30 A were measured, implying a plasma density of about 6 x10¹⁸ m^-3. This technology may prove useful for metal coatings free of noble gas inclusions and suggests that magnetrons could operate in the vacuum of space. In addition to coating objects in space, the momentum of the sputtered atoms and ions may be utilized in space thrusters.