The session opened with a keynote presentation on the 140 GHz, 1 MW gyrotrons developed for the Wendelstein 7-X stellarator in Germany. The talk was presented by G. Dammertz from FZK on behalf of a large team from a number of universities, laboratories, and companies throughout Europe. In recent tests, the "maquette" gyrotron demonstrated 1 MW output power at 10 second pulse lengths; 0.9 MW output power for 45 second pulses; 0.74 MW for 100 second pulses; and 0.64 MW for 140 seconds. A second gyrotron, with several improvements over the first, has been constructed and is currently in test at FZK. In the second talk, K. Felch detailed the recent progress on CW and long pulse gyrotrons for fusion applications at CPI. Experimental results for three 110 GHz, 1 MW power level gyrotrons; one 140 GHz, 1 MW power level gyrotron; and one 84 GHz, 500 kW gyrotron were discussed. Also, a summary of CPI’s experience with CVD diamond windows for fusion gyrotrons was presented. G.G. Denisov from Gycom presented results from a recent demonstration of a 1 MW 170 GHz gyrotron developed for ITER. Pulse lengths of up to 0.4 seconds were demonstrated at 950 kW peak output power and 44% efficiency with a boron nitride window. The boron nitride window was later replaced with a CVD diamond window for pulse width extension. K. Sakamoto from the Japan Atomic Energy Research Institute discussed the development of 1 MW power level 170 GHz and 110 GHz gyrotrons for fusion applications. At 170 GHz, 900 kW peak output power for 9.2 seconds has been demonstrated and at 110 GHz 1.2 MW for 4 second pulses was achieved. In the final talk of the session, G. Nusinovich from the University of Maryland presented a theoretical analysis of the effect of the radial thickness of electron beams on the stability in gyrotron oscillators.