FPN16-34

MIT Closes C-Mod Facility with an Exclamation Point

October 15, 2016

The last experiments on MIT's Alcator C-Mod facility were conducted late into the evening of September 30. The facility had been in operation for several decades, resulting in numerous important scientific discoveries. Scientists from many institutions in the U.S. and from around the world have conducted experiments at the facility. Operations have now ceased upon orders from the US government due to severe constraints on the overall fusion budget.

Scientists punctuated the final experiments with an exclamation point, by setting a new record for achieved average plasma pressure in tokamaks. Plasma pressure is the product of plasma density and temperature (nT). Expressed in units of typical atmospheric pressure, the latest result achieved was slightly over 2 atmospheres, with a plasma temperature of about 35 million degrees C. The previous record, achieved in 2005 also in C-Mod, was approximately 1.8 atmospheres. Other large tokamaks have typically operated at about 1.2 atmospheres. Power plants are expected to require close to 10 atmospheres, with temperatures of around 100 million degrees C. C-Mod differs from "conventional" tokamaks by operating at higher magnetic field strength and higher density.

A very large team of scientists from MIT, and other sites, conducted a series of experiments that led to the achievement. Scientists from MIT, Princeton Plasma Physics Laboratory, Oak Ridge National Laboratory and General Atomics were involved in the effort. The record setting run was led by Oak Ridge National Laboratory scientist Matt Rienke. Other key leaders of the effort to raise the plasma pressure included Earl Marmar of MIT (who will present the results at the IAEA Fusion Energy Conference in Kyoto), Jim Irby, Jerry Hughes and Steve Wolfe (MIT), Phil Snyder (GA) and Steve Scott (PPPL).

More details on the results are available at:

New record for fusion: Alcator C-Mod tokamak nuclear fusion reactor sets world record on final day of operation

and

Alcator C-Mod pressure record: FAQ More information on the significance of plasma pressure for magnetic fusion