Titanium, water-cooled vacuum chambers for SFRS

The first dipole stage of the super-FRS is situated in the target area and is formed by three 11-degree normal conducting (NC) dipoles. Due to the expected beam losses on the vacuum chamber walls, these dipoles must be able to withstand intense beam pulses. Intense beams scrape against the chamber wall at steep angles. Therefore, the chamber wall should be made of titanium alloy Ti6Al4V (3.7165) and water-cooled. A power of up to 2.4 kW with very localised energy deposition must be expected. In one single pulse energy densities up to 1 kJ/g can be reached. Because of its particular horn shape in the horizontal plane, the chamber's open aperture is defined by a rectangular profile with a constant vertical opening and a varying horizontal opening. The support structure, which holds the chamber in place, is also part of the delivery.

Vacuum interfaces between the vacuum chamber and neighbouring systems are provided via special "pillow seals" that operate at 1.5 to 2 bar above atmospheric pressure. A pillow seal exerts a large pushing force of up to 64.5 kN at the wide end and 39 kN at the narrow end.

Support structure design shall consider the forces exerted on the vacuum chambers by the pillow seals. The chamber and the support structure shall be able to withstand these forces.

There are two types of chambers defined as type 1 long and and type 2 which are differed by their length. Type 1 is 3200 mm long and a horizontal aperture minimum of 1122 mm at the wide end. Type 2 is 3650 mm long and horizontal aperture minimum of 1200 mm at the wide end. Both types has a vertical aperture minimum of 140 mm and 500 mm of horizontal aperture minimum at their narrow end. Contractor shall deliver one type 1 chamber and two type 2 chambers and the associated support structure.