Construction and beam experiment of a compact storage ring at MELCO

A compact storage ring has been developed for industrial research such as x‐ray lithography and material analysis. This machine is of a racetrack type with two superconducting bending magnets and only two normal conducting quadrupole magnets. The circumference is as short as 9.2 m. One quadrupole magnet per cell contributes to making the smaller machine. The injector is a synchrotron, and a full energy injection of 600 MeV is performed. The bending magnets excite a field of 3.5 T, and are operated in a persistent current mode. A decrease in a coil current is ΔI/I<3×10−3/year. The helium consumption is as low as 2 l/h for two magnets. An iron shield of the magnet decreases a leakage flux to a terrestrial level at a point 3 m from the magnet. A beam current of 380 mA has been stored with no beam instability in spite of there being no correction of the chromaticities. Beam emittances were obtained from measured beam sizes and were in good agreement with calculated values. The coupling coefficient ey/ex is ca...