Thruster for spacecraft

A thruster for a spacecraft, comprising:

• a housing adapted to serve as an anode and including an expansion nozzle, which has a constricted cross section region, and a wall having an inner surface, defining an annular plenum chamber;
• a rod member disposed in said annular plenum chamber, adapted to serve as a cathode and having a tip located upstream of said constricted cross section region in a spaced relationship thereto to form an air gap therebetween, through which gap an electric arc is generated upon application of positive and negative electrical potentials to said housing and said rod member, respectively;
• means for electrically insulating said rod member from said inner wall surface;
• and
• at least one tubular element connected with a source of a propellant gas and inserted into said wall of said housing with an orientation, which provides for injection of a stream of the propellant gas into said plenum chamber tangentially to said inner surface of said wall;
• wherein said thruster further comprises a pair of tubular elements wherein said tubular elements are inserted into said wall of said combustion chamber so as to be offset against each other by 180.degree., and further wherein said pair of tubular elements includes a shorter tubular element and a longer tubular element wherein the lengths of said tubular elements are unequal and further wherein said shorter tubular element has a diameter which is smaller than a diameter of said longer tubular element.