Technical Design Report Super Fragment Separator

2.4.11.1.4 Design of the beam catcher
Graphite part
DRAFT
From the discussions above the design of the beam catcher looks as follows: The entrance part
consists of graphite whereas the second part is made of iron. Figure 2.4.109 shows the graphite part
with the attached heat sink. The position of the cooling pipes with water is indicated. They run
inside the heat sink made of aluminium. Aluminium is chosen because of its good thermal conductivity
and lower mass number compared to copper. Still it needs to be sufficiently far away from
the main primary beam and may be hit only by far tails. Aluminium has also the advantage of
relatively low activation compared to copper.
The V-shape helps to distribute the heat better especially in the Bragg peak region and increases the
surface for better cooling. The iron part should be 60 cm long to sufficiently reduce the neutron
radiation for the subsequent magnet coils. The transverse size varies between 70 cm and 20 cm
depending on the individual catcher, see Figure 2.4.103.
After an initial heating phase the temperature reaches its equilibrium. The equilibrium distribution
was calculated using the ANSYS code [48] for the geometry depicted above. This simulation was
done assuming a turbulent flow of the water in several cooling tubes. The profile of the power
deposited was roughly adjusted to the fast extraction scheme as shown in Figure 2.4.105 and Figure
2.4.111. A volume with a spot size of (9 x 4.5) cm 2 and a depth of 9.1 cm was heated homogenously
with a total power of 23 kW corresponding to 6x10 11 238 U ions at 1500 MeV/u every 1.5s.
Figure 2.4.110 shows that the maximum temperature in a small spot in the centre of the beam
catcher becomes only 950°C in case of a DC beam. The walls of the cooling tubes stay below 50°C.
Figure 2.4.109: Construction of the beam catcher. The entrance part is made of graphite with a subsequent
part of 60cm iron which is not shown. The cooling water runs in copper tubes inside of an aluminium block in
close thermal contact to the graphite. The entrance is V-shaped to distribute the energy better and facilitate
the cooling over a larger surface. A heavy ion beam has at least 20cm of graphite in its path.
117