Non-invasive Profilers for the Cold Part of ESS Accelerator

International audienceSeveral Non-invasive Profile Monitors are being in-stalled along the accelerator to support the commissioning, tuning and operation of the powerful proton based ESS linear accelerator. In the low energy parts of the ESS linac (3.6 MeV to 90 MeV), the residual gas pressure is high enough to measure the transverse beam profile by using fluorescence induced by the beam on the gas molecules. However, in the ESS linac sections above 90 MeV, protons are accelerated by superconductive cavities working at cryogenic temperatures and high vacuum. Therefore, the signal based on the fluorescence process is too weak, while ionization can counteract this drawback. We have provided five IPM (Ionization Profile Monitors) pairs for energies ranging from 100 to 600 MeV. The design of such monitors is challenging due to weak signal (as a result of high proton energy and low pressure <10-9 mbar), tight space constraints inside the vacuum chamber, space charge effect, ISO-5 cleanliness requirement, and electrode polarization at ±15 kV. This publication will detail the development we followed to fulfil the ESS requirements