- The SPACE Channel:
Dr. Michel Laberge and Dr. Mark Henderson (ITER Organization) speak to the SPACE Channel about the new documentary Let There Be Light. Alongside the film's director, Mila Aung-Thwin, the trio entertained audiences at Toronto's Hot Docs Film Festival with a Q&A session following the screening of the film.
Speaker: Dr. Stephen Howard (General Fusion): General Fusion (GF) is operating a new sequence of plasma devices called SPECTOR (Spherical Compact Toroid) capable of generating and compressing plasmas with a more spherical form factor, avoiding the concave liner geometry used on previous compression tests at GF. SPECTOR forms spherical tokamak plasmas by coaxial helicity injection into a flux conserver (R= 19 cm, λTaylor = 23.9 m-1, minor radius of 8.3 cm) with a pre-existing toroidal field created by ≤ 500 kA of current in an axial shaft. The initial poloidal flux of up to 30 mWb and toroidal plasma current of 100 - 300 kA is formed rapidly in the spherical flux conserver during a Marshall gun discharge (850 kA peak, 90 ms duration), and then resistively decays over a time period of ~2 ms. SPECTOR 1 has an extensive set of plasma diagnostics including a surface magnetic probe array, 3 interferometer chords, visible and VUV spectroscopy, multi-point Thomson scattering as well as a 4-chord FIR polarimeter system in development. SPECTOR 2, 3 are mobile test platforms that can be transported out of the lab for compression tests. Plasma facing surfaces include plasma-sprayed tungsten and bare aluminum, and can be coated with ~5 mm of vacuum deposited lithium for the purpose of gettering impurities out of the base vacuum and to reduce the gas recycling coefficient of the wall. Working gas has included helium and deuterium. Experimental characterizations have been made of formation dynamics, MHD mode activity, evolution of plasma profiles during its lifetime, and trends in FWHM magnetic lifetime with respect to system control parameters. Control of safety factor profile q(Ψ) can be achieved through a choice of the amount and axial distribution of poloidal gun flux and the amount of shaft current. Grad-Shafranov equilibria are reconstructed from the surface magnetic data using Caltrans/Corsica. Ideal and resistive MHD stability can be tested with DCON and NIMROD over a range of pressure and current profile parameters. Realistic compression scenarios have been simulated using the 3D MHD code VAC. The SPECTOR geometry is stable for a wider range of plasma parameters than previous experiments at GF. Relatively hot (Te ≥ 400 eV) and dense (~1020 m-3) plasmas have achieved energy confinement times tE ≥ 100 ms and are being used in field compression tests.
Speaker: Dr. Michel Laberge (General Fusion): Magnetized Target Fusion (MTF) involves rapidly compressing an initial magnetically confined plasma by >300X volume compression. If near adiabatic compression is achieved, the final plasma can be heated to > 10 keV, and confined inertially to produce interesting fusion energy gain. General Fusion is developing a compression system using pneumatic pistons to collapse a cavity formed in liquid lead-lithium, heating a plasma target such as a spheromak or spherical toroid trapped in the cavity. With a low-cost driver, straightforward heat extraction, good tritium breeding ratio and excellent neutron protection, the concept is promising as a practical power plant. We will review the plasma formation and compression results achieved so far and our plans moving forwards. Work on the compression system will also be described.
Speaker: Blair P. Bromley (Chair, CNS Fusion Energy Science and Technology Division): An overview of alternative fusion concepts in Canada and internationally, including MTF/MIF devices, spherical tokamaks, magnetic mirrors and polywell devices, with a look at the state of the art at public and private ventures.
Speaker: Dr. Michel Laberge: General Fusion (GF) is a private company developing fusion energy with the ultimate goal of building a fusion power plant. We are using a novel technique called Magnetized Target Fusion (MTF), first proposed by the US Naval Research Lab in the 1970’s. In MTF, one first creates a magnetically confined moderately warm plasma of around 100 eV in a flux conserver. The flux conserver is then rapidly compressed. The magnetic field cannot penetrate the flux conserver on the time scale of the implosion. Magnetic field and plasma are compressed to the high temperature, magnetic field and pressure required for a fast fusion burn (microseconds).
General Fusion’s Magnetized Target Fusion system uses a ~3m sphere filled with molten lead-lithium that is pumped to form a cavity. A pulse of magnetically-confined plasma fuel is then injected into the cavity. Around the sphere, an array of pistons drive a pressure wave into the centre of the sphere, compressing the plasma to fusion conditions. This process is then repeated, while the fusion neutrons from the reaction are captured in the liquid metal and used to generate electricity via a steam turbine. A standard heat exchanger-steam turbine produces electric power, and some of the steam is recycled to run the pistons.
Initial plasmas with performance sufficient to do compression experiments have been developed. Because of the size and capital cost of building a large-scale piston driven compression system, plasma compression experiments presently form these plasmas in an aluminum flux conserver that is rapidly compressed using a chemical driver. The results of these experiments will be presented.
By harnessing the same process that powers the sun and the stars, fusion has the potential to be a zero-emission, safe and widely available source of energy.
Fusion runs on hydrogen, and this fuel must be heated to immense temperatures – over 150 million degrees Celsius – to release its energy.
Learn how a General Fusion power plant creates fusion energy with the infographic below, followed by full explanation of how the process works.
Fusion could provide an effective way of cleanly producing large amounts of energy, substantially reducing our reliance on fossil fuels.
For fusion energy to make it to the grid, it needs to be converted into electricity. While this seems simple, the design of many fusion power plants in fact makes it very difficult to extract the energy and convert it to a useful form. General Fusion’s power plant design overcomes this challenge, because it enables the use of existing steam turbine technology to produce electricity from fusion.
Learn how a General Fusion power plant converts fusion energy to electricity in the infographic below, followed by full explanation of how the process works.