Why do you need to attach an ion thruster to a reactor, if you can turn the reactor itself into a thruster? https://forum.kerbalspaceprogram.com/index.php?/topic/151286...
http://www.projectrho.com/public_html/rocket/enginelist.php
http://www.projectrho.com/public_html/rocket/enginelist2.php
http://www.projectrho.com/public_html/rocket/enginelist3.php
RD-600: Soviet bimodal GCNTR on page 2 is the one from that discussion