Portrait of Roger Raman

Roger Raman

The Electromagnetic Particle Injector (EPI) as a fast time response disruption mitigation system for tokamak-based reactors

Roger Ramen

University of Washington, Seattle

Wednesday, May 11, 2022


NW17-218 Hybrid

PSFC Seminars

Abstract: Predicting and controlling disruptions is an important and urgent issue for ITER. Some disruptions with a short warning time may be unavoidable. For these cases, a fast time response disruption mitigation method is essential. Experimental tests on a prototype system of a novel, rapid time-response disruption mitigation system being developed for tokamak-based reactors, referred to as the Electromagnetic Particle Injector (EPI), has been able to verify the primary advantages of the concept. These are its ability to meet short warning time scales of <10 ms while attaining the projected high velocities for deep radiative payload penetration in reactor-scale plasmas. The EPI relies on an electromagnetic propulsion system. A metallic sabot is accelerated electromagnetically to the required velocities (> 1 km/s) within 2 ms, at which point it releases well-defined microspheres, or a shell pellet, of a radiative payload. Initial experimental tests from the prototype system show attainment of over 600 m/s in about 1 ms. Essential aspects of payload separation from the sabot and sabot capture have also been demonstrated at 200 m/s, and the method can be extended to over 2 km/s.

Bio: Roger Raman holds a Ph.D. in Plasma Physics from the University of Washington (1990). After graduation, he worked for the Canadian Fusion Fuels Technology Project to develop an advanced fueling system known as Compact Toroid Injection. Since 1999 he has been employed by the University of Washington to develop a solenoid-free plasma start-up system known as Coaxial Helicity Injection (CHI). He is on long-term assignment to the Princeton Plasma Physics Laboratory (1999 to present), where he developed the transient CHI concept on the NSTX experiment.  Through collaborations with the QUEST facility in Japan and on the PEGASUS-III ST at the University of Wisconsin, he is now involved in developing a reactor-relevant CHI configuration. More recently, he has been involved in the development of a fast time response tokamak disruption mitigation system known as the Electromagnetic Particle Injector (EPI). Dr. Raman has been an active Physics Operator on NSTX and was the Experimental Run Coordinator for the 2006 and 2009 NSTX Run campaigns, and before graduate studies was also trained as Reactor Shift Engineer for the NRU fission Research Reactor at the Atomic Energy of Canada Limited.