Development of large radio frequency driven negative ion sources for fusion

A new large area, high power rf source for negative ion beam systems has been developed. The source operates very reliably and has the potential for long pulse operation. Current densities up to 15 mA/cm(2) could be extracted with a cold plasma grid at 0.65 Pa source pressure. By pure volume production 9 mA/cm(2) current density at the same pressure level has been achieved with the addition of argon to the source operating gas. (C) 2000 American Institute of Physics. [S0034-6748(00)53402-9].