Status and commissioning plans for LHC Run 2. The RF system.

The paper presents the work done on the LHC RF system during Long Shutdown 1 (LS1). On the High Level side we have replaced a cryomodule (four cavities, beam 2), which could not operate reliably at the design voltage (2 MV per cavity). The upgrade of klystron collectors has been completed and new crowbar systems have been installed (solid state thyristors replacing the old thyratrons). On the Controls side, all RIO3 CPUs are beeing replaced and the new ones are now using Linux. The new FESA classes are being designed with FESA3. The consequences of the increased beam current (0.55 A DC compared to 0.35 A in 2012), the increased energy (physics planned at 6.5 TeV/c per beam), and the exotic bunch spacing (5-20 ns for the scrubbing beams) will be analyzed from an RF hardware point of view. A tracking code is being developed to understand the effect of coloured phase noise on the longitudinal bunch profile. The expected benefits are the optimization of the blow-up and the possible shaping of bunch profile (flatter bunches) to avoid beam induced heating and improve beam stability. Upgraded longitudinal bunch-by-bunch measurements are being implemented.