My return fellowship project is proposed to be the commissioning of the injector of the Athens Cascade Racetrack Microtron (RTM). The Athens RTM of the Institute for Accelerating Systems and Applications (IASA) is now under construction. The injector consists of a 100 keV thermionic electron gun, an RF system that chops and bunches the beam, two accelerating sections that raise the beam energy to 5 MeV for insertion into the RTM and a beam profile measurement line. The proposed project involves the modification, installation and operation of the injector obtained from the National Institute for Standards and Technology (NIST, Washington). At a later stage I will begin working on a design of a polarized electron source, taking advantage of the expertice that I have obtained working on a similar project at NIKHEF. IASA being affiliated with the National and Capodistrian University of Athens and the National Technical University of Athens, can provide me both with all the necessary means for the successful completion of the project and environment conducive to my reintegration into the Greek scientific community.