COMPARISON OF SMCO AND NDFEB IN PM MULTIPOLES

We study the use of such compounds in the strong, permanent magnet multipoles required for handling high energy, charged particle beams. We have made a number of SmCo/sub 5/ multipoles which have been used in a variety of ways, e.g., sextupoles for chromatic correction of the SLAC damping rings and quadrupoles for matching their associated injection and extraction lines. For applications in high radiation areas, we have used VACOMAX 170 thermally stabilized at 80/sup 0/C. Because our fabrication method uses measured characteristics of individual blocks in isolation, linearity over the operating range of the B-H curve is important. Stronger PM materials or multipole magnets increase the operating range which decreases linearity and increases unwanted harmonics. To study such effects, multipole magnets of VACODYM 370 are being made at different radii to emphasize high field effects which can drive parts of a magnet well into the third quadrant of the B-H curve. The results are compared to calculations based on various assumptions and our previous results for SmCo.