Design and manufacturing of permanent magnet bearing rings for high speed applications

We provide an overview of the challenges for the design of magnet rings for high-speed permanent magnet bearings focusing on manufacturing aspects. We analyze an assembly of a NdFeB magnet ring with a hub and a bandage, both made of Ti-6Al-4V (titanium grade 5). Thereby, we consider bandage thicknesses, tolerances and assembling processes. This is supported by simulations using Finite Element Method (FEM) analysis in ANSYS workbench 2020. We analyze the stresses during a press-fit joining process between the magnet and the bandage and subsequent consequences for the stresses on the system for rotation speeds up to 120,000 RPM. Finally, we consider safety aspects by implementing a cracking of the magnet at high rotation speed. The results of the simulations show that the stresses on the magnet are the limiting factor of the rotation speed in all cases analyzed here. For an idealized system, mainly the bandage thickness and the required rotation speed define suitable tolerancesfor the fitting of the bandages and magnets. For a real system, residual stresses of the joining process and ovalization effects of the bandage decrease either the allowable speed or the allowable tolerances, thereby considerably influencing the required manufacturing precision. A safety analysis shows that the hub-magnet-bandage assemblies analyzed here are safe with respect to magnet cracking even at high speed

Chopper system for time resolved experiments with synchrotron radiation

10 pagesInternational audienceA chopper system for time resolved pump-probe experiments with x-ray beams from a synchrotron is described. The system has three parts: a water-cooled heatload chopper, a high-speed chopper, and a millisecond shutter. The chopper system, which is installed in beamline ID09B at the European Synchrotron Radiation Facility, provides short x-ray pulses for pump-probe experiments with ultrafast lasers. The chopper system can produce x-ray pulses as short as 200 ns in a continuous beam and repeat at frequencies from 0 to 3 kHz. For bunch filling patterns of the synchrotron with pulse separations greater than 100 ns, the high-speed chopper can isolate single 100 ps x-ray pulses that are used for the highest time resolution. A new rotor in the high-speed chopper is presented with a single pulse (100 ps) and long pulse (10 μs) option. In white beam experiments, the heatload of the (noncooled) high-speed chopper is lowered by a heatload chopper, which absorbs 95% of the incoming power without affecting the pulses selected by the high speed chopper

Tuning the instrument resolution using chopper and time of flight at the small-angle neutron scattering diffractometer KWS-2

Following demand from the user community regarding the possibility of improving the experimental resolution, the dedicated high-intensity/extended Q-range SANS diffractometer KWS-2 of the Jülich Centre for Neutron Science at the Heinz Maier-Leibnitz Center in Garching was equipped with a double-disc chopper with a variable opening slit window and time-of-flight (TOF) data acquisition option. The chopper used in concert with a dedicated high-intensity velocity selector enables the tuning at will of the wavelength resolution [Delta][lambda]/[lambda] within a broad range, from 20% (standard) down to 2%, in a convenient and safe manner following pre-planned or spontaneous decisions during the experiment. The new working mode is described in detail, and its efficiency is demonstrated on several standard samples with known properties and on a completely new crystallizable copolymer system, which were investigated using both the conventional (static) and TOF modes