  Four decades ago development of high-current superconducting NbTi wire cables
revolutionized the magnet technology for energy frontier accelerators, such as
Tevatron, RHIC and LHC. The NbTi based magnets offered advantage of much higher
fields B and much lower electric wall plug power consumption if operated at 4.5
K but relatively small ramping rates dB/dt << 0.1 T/s. The need for the
accelerators of high average beam power and high repetition rates have
initiated studies of fast ramping SC magnets, but it was found the AC losses in
the low-temperature superconductors preclude obtaining the rates in the excess
of (1- 4) T/s. Here we report the first application of high-temperature
superconductor magnet technology with substantially lower AC losses and report
record high ramping rates of 12 T/s achieved in a prototype dual-aperture
accelerator magnet.
