EFFECTIVE ACTIVATION-ENERGY OF 16MEV PROTON-IRRADIATED QMG-YBCO

Ion irradiation effects on improvement of flux-pinning properties for quenched and melt growth YBCO samples (QMG-materials) were studied. Ir radiation with 16MeV protons was performed up to a dose of 1 x 10(16)p /cm(2). The effective activation energies of vortices are expressed wi th the formula, U-eff = g(T)h(H)f(J) proportional to (J/J(c))(-alpha) [1 - (T/T-x)(2)](2/3) H--1/3 at lower irradiation doses below 5 x 1 0(15)p/cm(2). The J-dependence of U-eff changes from power-law to ques i-exponential dependence with an increment of irradiation dose.