Water Cooled Beryllium Windows are an Atlas Specialty.
Because of the unique quality of a metal sandwich SS/CU/SS with copper in the middle of the sandwich, a beryllium foil is brazed to the copper and water is directed near the window for cooling. The stainless steel sides of the sandwich are welded to standard CF-Flanges. Reticles are located on the flanges for laser alignment.
Beryllium Windows are specified by Synchrotron Ring and Beam-Line scientists and engineers.
There are many parameters that lead to a specification.
A typical Beryllium window specification defines:
- The window clear aperture (H x V) (50mm x 16mm,minimum)
- Window thickness
- Number of apertures
- Thickness (example: PF-60 brand 0.20mm +/- 10%)
- Surface finish (better than 2μm)
- Beryllium purity (>99%)
- Protective Coating: The protective coating on the air side of the Be foil is made of Boron Nitride / BR-127 primer or equivalent. The protective coating will transmit 95% of photon energies greater than 4 keV.
- Vacuum UHV compatible and able to sustain pressure difference 1 bar. Leak Rate: less than 10-9 mbar lit/sec He
Cooling: The Be window is brazed to a copper block. The block is water cooled so that the Be window can sustain the thermal load from synchrotron radiation passing through the window (total power = 90 W, max density = 0.40 W/mm2. Water in-out Swagelok fitting mounted to copper block. Cooling tube with U-shaped return line.