Nonlinear instantons from supersymmetric p-branes

Supersymmetric configurations of type-II D-branes with nonzero gauge field strengths in general supersymmetric backgrounds with nonzero B fields are a nalyzed using the kappa -symmetric worldvolume action. It is found in dimen sion four or greater that the usual instanton equation for the gauge field obtains a nonlinear deformation. The deformation is parameterized by the to pological data of the B-field, the background geometry and the cycle wrappe d by the brane. In the appropriate dimensions, limits and settings these eq uations reduce to deformed instanton equations recently found in the contex t of noncommutative geometry as well as those following from lagrangeans ba sed on Bott-Chern forms. We further consider instantons comprised of M5-bra nes wrapping a Calabi-Yau space with non-vanishing three-form field strengt hs. It is shown that the instanton equations for the three-form are related to the Kodaira-Spencer equations.