Measurements on the first LHC acceleration module

The Large Hadron Collider (LHC), now under construction at CERN, will accelerate the two counterrotating beams of protons from an injection energy of 450 GeV to the coast value of 7 TeV where they will collide. The main accelerating system for each beam comprises eight 400 MHz superconducting cavities giving a total of 16 MV. The cavities are grouped in fours in cryogenic modules to ease installation and reduce heat losses. The different requirements at injection and collision together with the heavy beam loading have imposed the use of a variable power coupler (the coupling can be varied by a factor 10) and a tuner with 180 kHz range. The 300 kW power is supplied by a klystron attached to the cavity via a circulator. The first module with its four cavities has now been assembled at CERN and tested. The results from these measurements are presented, problems encountered are described and modifications to be applied in the future are given.