IMP (Institute of Modern Physics) has been developing a
Quadrupole-Sextupole nested CCT (Canted Cosine Theta Type) prototype
for the HFRS (High Energy Fragment Separator) beamline of HIAF (High
Intensity Heavy-ion Accelerator Facility) project. Hence a matrix
harmonic coil method has been developed for magnetic field quality
measurement of multi-pole nested magnets. Furthermore, a whole set
of measurement system has been constructed and some special
mechanical components, like cold bore, have been set up to cooperate
with matrix harmonic coil measurement. After cold test at 4.2 K,
the measurement results prove that the prototype property and field
quality basically meets our requirement, and matrix harmonic coil
also functioning well.