5.3 Space limitations

High-power, high-energy neutral beam injectors are large; for example, the ITER 1 MeV heating injectors are ≈15 m long and ≈4 4 m in cross section, and the high voltage bushing through which connects the power, gas, and water cooling to the beam is over 6 m tall and 2.5 m in diameter (see Figure 2).

Obviously the injectors will require a large "neutral beam cell" somewhere around the reactor, which must also provide space around the injectors for nuclear and magnetic shielding, and, because the injectors on a reactor will become radioactive, space for the remote handling equipment needed for all maintenance on the injectors. Space around the reactor will also be required for many other types of equipment, and the space for the injectors will inevitably be limited, which will directly influence the design and layout of the injectors and any attachments to the injectors. Some appreciation of the likely space constraints can be gained from the ITER system. The layout of the three heating and one diagnostic neutral beam injectors is shown in Figure 3.
