Indus-2 Vacuum Chambers

UHVT Division is responsible for the design, material procurement, fabrication, cleaning, testing, integration and evacuation of all the vacuum chambers in INDUS-2 storage ring. The vacuum envelope consists of bending (dipole) magnet (BM) chambers, straight section chambers along with other diagnostic components. The vacuum system was designed based on the design of lattice with magnets’ positions.

The chamber profile was designed taking the good field region into consideration. This profile was maintained in all the dipole chambers and straight section chambers and other  components.

The BM chambers were made of 5083-H321 Aluminium alloy. Each chamber was made of 2 plates of size 4000mm x 900mm x 75mm  machined to a profile  to get accommodated in  dipole magnets and  quadrupole magnets. The minimum thickness calculated was 4.5 mm, which was maintained at the critical areas.  The plates are machined into a top half and a bottom half to be joined in the middle plane and a  welding lip was provided all along this plane to weld the top and bottom plates together. Side covers for this chamber was also machined from the same material along with the lip.  The chamber was chemically cleaned before welding and leak tested after welding. The chambers got qualified for a leak rate ~ 2 X 10^-10 mbar l/sec. All such chambers were tested for ultimate vacuum after subjecting them to baking for 48 hrs with  super heated water at 150 °C.  Ultimate vacuum achieved was  in the range of  5 x10^-10 mbar  and  1x10^-9.  mbar.

Dipole magnet chamber just after welding

Dipole magnet chamber during UHV testing

The straight section  chambers  were made of extrusions of Aluminium alloy 6063-T6. These chambers were made of different lengths and locally machined to accommodate within the quadrupole, sextupole and corrector magnets. Pump ports and gauge ports are  provided at the required locations. The flanges to join them are of different seal configurations, like conflat, helicoflex and diamond type. They are all welded, leak tested and  tested for UHV as in dipole chambers. For the continuity of RF current to be maintained, the joint gaps are filled with Beryllium copper fingers.

Straight section chambers during UHV testing