Figure 3 illustrates the configuration of the first wall
reference designs.
Both consist of tube sheets with coolant flowing in the poloidal direction. Immediately behind the first wall is the beryllium multiplier. The inner diameter of the coolant channels is 7.5 mm. The vanadium alloy design uses liquid lithium as a coolant; the SiC composite design uses helium. Note that the SiC composite design includes a sacrificial carbon-vapor-deposited (CVD) SiC layer to extend the first wall life against erosion.
The PULSAR divertor designs are similar to the first wall configurations. The vanadium divertor has a larger inner diameter (10 mm). The SiC divertor is made of free-standing tubes with an inner diameter of 5 mm. In addition, the sacrificial layer is absent from the SiC divertor design.