Fig. 5. Distribution of forces and currents induced in the tungsten blocks during the oscillation of the non-monotonic phase in (left) and the monotonic phase in (right). points distributed along three different sections of the beam screen, optical fibers to measure axial and transversal strains on the outer surface of the cold bore, and three custom made probes to integrate the previously described displacement sensors in order to measure the expansion of the beam screen, the tilt of the tungsten alloy heat absorber during the CLIQ phase and the magnetic field. Special probes were developed to measure the expansion of the beam screen (single pin side) and the tilt of the tungsten blocks (double pin side). In addition, pick-up coils were mounted in the central probe to measure the magnetic field and have further data to analyze the mechanical response of the beam screen, as shown in Fig. 6. Two strain gauges to compensate the signals of all the probes were installed on two free-pin strips of the upper probe. The structure of the probe is made of G-11 FR-5 glass fiber reinforced plastic and is designed to be auto-equilibrated within the beam screen by means of the displacement sensors whose pins push against the inside of the beam screen or tungsten alloy heat absorbers (Fig. 6). Eight sensors are mounted in the probe: four for each side. The expansion of the beam screen is measured by the side of the probe where there are single strips. The tilt of the heat absorber is measured by the other side of the probe where two strips are placed next to each other in its upper and bottom side. Additionally, two identical displacement sensors located in two perpendicular faces of the central probe at 45° with respect to the poles of the magnet and non-mechanically connected to the structure are included in the set-up in order to ascertain the effect of the magnetic fields in the sensors. This mechanical configuration is much less favorable than the one for the rest of the sensors, as the sensors nonmechanically connected to the structure are cantilevered, while the sensors used for the determination of the expansion of the beam-screen and the tilt of the tungsten sensors are Fig. 6. (a) Probe with displacement sensors and pick-up coils. (b) Expansion and tilt measurement configuration. 44 IEEE Instrumentation & Measurement Magazine December 2021