Divergent quench velocity expression and 4-cm SSC R and D dipole magnets

When a normal zone, with dimensions larger than the minimum propagation zone (mpz), is formed in a superconducting (s.c.) cable, it propagates along the conductor with a so-called axial quench velocity, and the phenomenon itself is called quench. When the s.c. cable is used to form the coil of a superconducting magnet, the store energy of the magnet is dissipated in the coil in the form of heat generated by the normal zone of the s.c. cable. Special care must be taken to protect the magnet against overheating or major damage may occur in the event of a quench. A quench velocity expression which has a divergent behavior close to the critical current density is reported here. This quench velocity has the same behavior presented by that of the quench velocity measurements made on the 17-m-long, 4-cm-aperture SSC R and D dipole magnets which show a clear departure from the expected theoretical adiabatic expression