Design and Test of Magnetic Shields for Turbomolecular Pumps and Quadruple Mass Spectrometers

The use of turbomolecular pumps and quadrupole mass spectrometers in plasma experiments set troublesome problems because of the presence of static magnetic fields. The utmost consequences of this interaction are very adverse: the break of the turbomolecular pump and the entire loss of the signal in the quadrupole instruments. Here, the need to protect against the magnetic field hazard the vacuum devices connected to a plasma experiment has been the thrust for the study and fabrication of appropriate magnetic shielding systems. This work summarizes the procedures taken for the development of the magnetic shields, providing guidelines that can be applied to any experiments that involve the presence of static magnetic fields, also for vacuum devices exposed to the stray magnetic field of large tokamak as ITER. A worthy compromise between costs and performances together with a simple design of the shield structure have been the primary approach in the present work.