LIGO Mechanical and Vacuum

Overview

LI-Mechanical & Vacuum Section is formed to provide support to Vacuum System of LIGO-India Mega Science project being setup at Aundha in Hingoli District of Maharashtra. This is the first mega science project that is coming up in the country. Responsibilities of LI-MVS include – providing entire support for construction of Vacuum Infrastructure at the project site. TDCB (Technology Development and Capacity Building) phase of the project has been successfully completed in which LI-MVS has made significant contribution towards prototype activities in the form of fabrication, inspection and testing of 1:1 scale prototype of BSC, HAM chamber, 10m Vacuum Vessel (resembling beam tube of the main project), 80K Cryopump and expansion joints (Bellows). This phase has helped the main project to establish Material qualification, manufacturing process, inspection and testing procedures etc. Now LIGO India has entered in project procurement phase by floating Tender for the construction of Civil and Vacuum Infrastructure at the project site, where LI-MVS has complete responsibility for vacuum infrastructure.

LIGO Mechanical and Vacuum

Activities

1.Outgassing Measurement Facility to estimate hydrogen outgassing rate from stainless steel sheet material.

This facility setup is in operation at LIGO Lab in IPR. The facility is mainly used to measure hydrogen outgassing rate from austenitic stainless steel. Preliminary outgassing measurements trials with coupons cut from raw material and air baked material (S.S. 304L grade) for hydrogen outgassing estimation of stainless-steel raw material have been successfully performed and further fine tuning of setup to improve upon the precision of measurements is in progress. The qualification parameter for hydrogen outgassing rate is < 5 x 10-14 mbar l/s/cm2 for stainless-steel raw material used in the construction of LIGO-India beam tube sections. This facility has been setup to establish raw material qualification procedure.

2.LIGO-India – Vacuum Integrated System Test Assembly (LI-VISTA).

LI-VISTA constitutes 20m long tube and a long 80K cryopump isolated by a large gate valve of aperture 1.2m. As a part of prototype activities of LIGO-India project, LIGO Division manufactured 20 m vacuum vessel assembly and 80K Cryopump Assembly. Both these assemblies along with the vacuum equipments & accessories and their respective control and monitoring system have been integrated in the LIGO Lab. This integrated test facility setup is christened as LI-VISTA (LIGO-India – Vacuum Integrated System Test Assembly). This facility is planned to be used as a test bed to evaluate the vacuum performance of vacuum vessel, vacuum equipments along with the vacuum pump-down scenarios as a part of the assessment of corresponding beam tube pump-down for main LIGO-India project. So far ultimate vacuum accomplished in the LI-VISTA facility is 1.36 x 10-9 mbar in the vessel having volume of ~26 m3. Vacuum requirement for LIGO operation at its designed parameters is ≤ 1.00 x 10-9 mbar. Necessary vacuum equipments and accessories installed in this facility include vacuum pumps – TMP’s, Ion Pumps, Gauges, RGA’s and gate valves of different sizes including one large GV (1250 NB).