Conditional Well-Posedness for an Inverse Source Problem in the Diffusion Equation Using the Variational Adjoint Method

This article deals with an inverse problem of determining a linear source termin themultidimensional diffusion equation using the variational adjoint method. A variational identity connecting the known data with the unknown is established based on an adjoint problem, and a conditional uniqueness for the inverse source problem is proved by the approximate controllability to the adjoint problemunder the condition that the unknowns can keep orders locally. Furthermore, a bilinear formis set forth also based on the variational identity and then a norm for the unknowns is well-defined by which a conditional Lipschitz stability is established.