Physics design calculations for the JET neutral injectors

The first results of physics design calculations for the JET neutral injectors are presented with the reference to beam transmission and geometric losses, vacuum calculations and reionization losses and beam blocking. The pulse length and the beam transmission required to achieve the specified performance considerably exceed that of present generation beam lines. An installed pumping speed of > or approx. 4 x 106 l s-1 will be required to keep total ionization losses to approx. 10%. Preliminary calculations indicate that beam blocking should not occur. (author)