Properties of the JET 130kV/60A positive ion neutral injector

As part of the upgrade to the JET neutral beam heating system a new positive ion neutral injector (PINI) design has been commissioned. The new PINI delivers 60A total beam current at 130kV, approximately doubling the neutral beam power delivered to JET. A programme of testing on the Neutral Beam Test Bed established the preferred geometry to maintain horizontal and vertical beam focal lengths of 10m and 14m respectively. The results of these tests and the characterisation of the beam using a number of diagnostic techniques are described, together with predictions for neutral power delivery to the JET plasma.