Atomic level lifetimes have been measured on magnetic dipole (M1) transitio
ns in Si-like, P-like, Ar-like, K-like, and Ca-like ions of Kr, using an el
ectron-beam ion trap in magnetic trapping mode. The lifetimes are compared
to various predictions, including the results of different calculations. In
Ar-like ions, magnetic quadrupole (M2) transitions have been identified as
significant competing decay channels.