The hydrostatic levelling system (HLS)/servo-controlled precision jacks: a new generation altimetric alignment and control system

In 1987 the ESRF paved the way for a new ambitious accelerator alignment to satisfy demanding and as yet unachieved design specifications. This consists of a permanent realignment of the magnetic elements distributed over the 1 km circumference of the storage ring to an absolute horizontal plane with a precision of ±1 mm. Relative alignment precision is specified at ±0.1 mm between two adjacent elements. Realignment operations are performed in less than one day. In 1989 once laboratory tests confirmed that each of the “Hydrostatic Levelling System” and jack prototypes were capable of achieving the desired results, the series production of the 300 each of HLS and Jacks necessary to align the ESRF storage ring was launched. From April 1991 thru´ January 1992 the installation of girders in local mode was made in record time, to which the HLS made a significant contribution. During the so called storage ring “Commissioning Phase” (running from January 92 thru´ June 92) the software was written, installed all equipment connected to the control room. Today we would like to present the results of the first storage ring alignment which took place on January 10 1993. Results obtained were ten times better than those stipulated in the specifications and duly confirm that in less than one day it is possible to align a 1 km circumference storage ring with an absolute precision of ±0.1 mm/km and a relative precision between girders greater than 10 μm