1. AdV TCS overview (quick) V. Fafone and A. Rocchi

2. Advanced LIGO-like solution Green dots: shielded heating ring Blue rectangles: CP Compensation plates will correct thermal effects in the PRC Shielded heating rings will compensate HR surface deformations TCS scheme In the case of Advanced Virgo, the positioning of CPs in the PRC is a delicate issue due to its interaction with the suspension systems

3. Compensation plate – The CP is foreseen to be attached to the ITM reference mass, noise motion requirement is expected to be easily met. – The most feasible solution is to fix the CP on the back of the reference mass. – The clear aperture due to the coil-magnet actuators on the back of the RM is 280 mm, a maximum diameter of 280 mm for the CP is foreseen, while the thickness will be of about 7-10 cm. – Design is in progress

4. Shielded ring heater design guidelines RH TM RH HR Surface Developing FEA to optimize the position/power of the heating ring. Result for a TM heated by a simple ring - no shielding included yet, lower power is expected to give the same ROC correction. SRH modeling is in progress

5. AXICON profiles AXICON profiles with fixed outer radius (14cm) to illuminate the whole CP Inner radius going from 35mm to 75mm in steps of 5mm CO 2 power ranging from 3.5W to 10.25W in steps of 0.25W 280 simulations for each setup

6. CP close to the TM (1cm) Thickness 6.5cm Vertical scale is the Log(L) Minimum L is 10 4 ppm RH effect reduced by the heat radiated from the CP ROC from 1530m to 1523m Less RH power needed! RH power definition is in progress Corresponding OPL TM heated by radiation from the CP

7. CP heating pattern In Virgo+, TM heated with a profile given by an AXICON J.Y. Vinet and J. Degallaix found (independently and with different approaches) that the best heating pattern would look like this But this profile does not take into account radiative coupling btw TM and CP and the presence of the RH. Work in progress to find the optimum profile to minimize coupling losses in the complete set-up. Compensating mask for a TEM 00 mode w=2 cm Compensating mask for Gingin HOPTF