Application of Magnetically Insulated Transmission Lines for high current. High voltage electron beam accelerators

Self Magnetically Insulated Transmission Lines (MITL) adders have been used successfully in a number of Sandia accelerators such as HELIA,¹ HERMES III,² and SABRE.³ Most recently we used a MITL adder in the RADLAC/SMILE electron beam accelerator to produce high quality, small radius (r_b <; 2 cm), 11 to 15 MeV, 50 to 100-kA beams with a small transverse velocity v⊥/c = β ⊥ ≤ 0.1⁴ In RADLAC/SMILE, a coaxial MITL passed through the eight, 2 MV vacuum envelopes. The MITL summed the voltages of all eight feeds to a single foilless diode. The experimental results are in good agreement with code simulations. Our success with the MITL technology led us to investigate the application to higher energy accelerator designs. We have a conceptual design for a cavity-fed MITL that sums the voltages from 100 identical, inductively-isolated cavities.⁵ Each cavity is a toroidal structure that is driven simultaneously by four 8-ohm pulse-forming lines, providing a 1-MV voltage pulse to each of the 100 cavities. The point design accelerator is 100 MV, 500 kA, with a 30-50-ns FWHM output pulse.