  This paper is the first input towards an open analogue of the quantum Kirwan
map. We consider the adiabatic limit of the symplectic vortex equation over the
unit disk for a Hamiltonian G-manifold with Lagrangian boundary condition, by
blowing up the metric on the disk. We define an appropriate notion of stable
solutions in the limit, and prove that any sequence of disk vortices with
energy uniformly bounded has a subsequence converging to such a stable object.
We also proved several analytical properties of vortices over the upper half
plane, which are new type of bubbles appearing in our compactification.
