Open waveguide electromagnetic wave radiator for secondary heating a plasma in a nuclear fusion reactor

An open waveguide electromagnetic wave radiator for heating a plasma, in a nuclear fusion reactor comprising:

• an RF heater, including a waveguide having an opening at one end directed to the plasma through a radiator portion, a short circuited end at the other end of the waveguide, a pair of ridges extending between the opening and the short circuited end, each ridge having a T-shaped cross section, each ridge connected to a respective inner surface side of said waveguide, with evacuation means made in at least one of said inner surface sides;
• evacuation pipe means connected to said evacuation means, said pipe means having an internal chord D passing through the center of the cross section of said evacuation pipe means and a length L of said evacuation pipe means, said chord D and length L are determined in accordance with an evacuation conductance C, where C=121.times.(D.sup.3 /L) and a leak power ratio P.sub.l, where P.sub.l =A.times.exp (-7.3647.times.L/D) where A is a constant which depends on the waveguide dimensions;
• and
• pump means adapted to be connected to said evacuation pipe means for evacuating gases from the inside of said waveguide.