%0 Journal Article %T Determination of critical current density from arbitrary flux relaxation process %A Rongchao Ma %J AIP Advances %D 2012 %I AIP Publishing LLC %R 10.1063/1.3681281 %X The current-carrying ability of a type-II superconductor is generally represented by its critical current density. This can be determined by measuring a flux relaxation process starting with a testing current density that is greater than or equal to the critical value. Here we show that a flux relaxation process starting with an intermediate current density can be converted into a process starting with the critical current density by introducing a virtual time interval. Therefore, one may calculate the critical current density from the flux relaxation process starting with a current density below the critical value. The exact solutions of the time dependence of current density in the flux relaxation process were also discussed. %U http://link.aip.org/link/doi/10.1063/1.3681281