  We consider the formation of a ring-like magnetic field in collisions of
bubbles of broken phase in an abelian Higgs model. Particular attention is paid
on multiple collisions. The small collision velocity limit, appropriate to the
electroweak phase transition, is discussed. We argue that after the completion
of the electroweak phase transition, when averaged over nucleation center
distances, there exists a mean magnetic field $B\simeq 2.0\times 10^{20}$ G
with a coherence length $9.1 \times 10^3 GeV^{-1}$ (for m_H=68 GeV). Because of
the ring-like nature of B, the volume average behaves as $B \sim 1/L$. Taking
into account the turbulent enhancement of the field by inverse cascade, we
estimate that colliding electroweak bubbles would give rise to a mean field
$B_{rms}\simeq 10^{-21}$ G at 10 Mpc comoving scale today.
