The neutral beam heating and current drive system in ITER consists of 3 beam lines (2 present plus one future upgrade) with each beam line designed to deliver 40 A of accelerated deuterium beams at 1 MeV with a 25% duty cycle. The beam line is coupled to the vacuum vessel port of the tokamak through a series of front end components and a connecting duct. The edge of the beam line and the walls of the vacuum vessel up to the blanket aperture are lined with duct liners to protect them from heat loads from the direct and re-ionised beam interception during the transport of the neutral beam. The direct interception of the beam is due to the inherent divergence of the beam or its halo component. The re-ionised beam consists of ions born due to the interaction of the accelerated neutral beam with the back ground gas all along the beam line, after the neutraliser exit. The motion of these ions is also affected by the electric field of the residual ion dump (RID) and the magnetic field from the tokamak during its...