page_title: General Fusion
section_title: Compression driver technology
hierarchical_section_title: General Fusion / Research and development / Compression driver technology
caption_attribution_description: General Fusion reactor for magnetized target fusion. The large pistons are used to pump liquid metal in order to compress the plasma.
context_page_description: General Fusion is a Canadian company based in Burnaby, British Columbia, which is developing a fusion power device based on magnetized target fusion. The company is funded by a variety of investors.
  The fusion device under development injects plasma in the form of a compact toroid into a hollow cylinder, which is then compressed to fusion-relevant densities and pressures. In contrast to most MTF systems, which use magnets to compress the plasma, the General Fusion design instead uses a large number of steam-driven pistons to mechanically compress a vortex of liquid metal. As of 2017 General Fusion was developing subsystems for use in a prototype to be built in three to five years.
  In 2018, the company published several papers on a new design using a spherical tokamak as the plasma source, as opposed to the compact toroid. It is not clear in existing references whether this represents a major change of the original concept.
context_section_description: Pneumatic pistons were initially used to create a converging spherical wave to compress the plasma. Each system consists of a 100 kg, 30 cm diameter hammer piston driven down a 1 m long bore by compressed air. The hammer piston strikes an anvil at the end of the bore, generating a large amplitude acoustic pulse that is transmitted to the liquid metal in the compression chamber via the piston anvil. To create a spherical wave, the timing of these strikes must be controlled to within 10 µs of each other. The company has recorded sequences of consecutive shots with impact velocities of 50 m/s and timing synchronization within 2 µs.
  A proof-of-concept prototype compression system was constructed in 2013 with 14 full size pistons around 1 meter diameter spherical compression chamber to demonstrate pneumatic compression and collapse of a liquid metal vortex.
caption: Pistons for plasma compression
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