The present disclosure generally provides methods and apparatus for efficiently crosslinking silicon carbide fiber precursor polymers with electron beam radiation. The methods and apparatus utilize a platform (14, 114) containing silicon carbide fiber precursor polymer (16, 116). The temperature of the platform (14, 114) is regulated while the silicon carbide fiber precursor polymer (16, 116) is irradiated to thereby regulate the temperature of the irradiated silicon carbide fiber precursor polymer thereon. In this way, the temperature of the irradiated silicon carbide fiber precursor polymer (16, 116) is regulated via the platform (14, 114) both during and after it is subjected to radiation. At least one of the platform (14, 114) and the e-beam radiation mechanism (12, 112) may be translated with respect to the other to irradiate different portions of the silicon carbide fiber precursor polymer (16, 116) and, ultimately, the entirety of the silicon carbide fiber precursor polymer contained on the platform (14, 114).