Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

We describe results of optimization of the extraction magnet of a 55 MeV Race-
Track Microtron (RTM). Because of small spacing between the RTM orbits special
attention has been paid to optimization of magnetic screens with the aim to decrease the influence of stray magnetic fields on the accelerated beam. Results of simulations with 2D and 3D codes are compared with magnetic field distribution measurements.