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Principal physics targets

  • The behavior of the diverter and the process of scraping off a layer;
  • Ramp-up features;
  • Transport management.

Specific programmatic goals

  • Showcase the ability to effectively increase and maintain performance for durations significantly longer than typical restrictions and timeframes;
  • Investigate scaling of energy confinement for a wide variety of factors;
  • Scaling and coupling in core and edge confinement;
  • A combined understanding of theory, simulation, and experiment;
  • Create and display first-order active plasma regulation.
  • Wall Conditioning/Pumping Systems

    • CV gettering – 14 Ti-arc rods – 1 M L/s;
    • 32 Ti-arcs w/ LN2 system per diverter – 2 M L/s;
    • Base pressure ~10-10 torr;
    • Improved wall condition and impurity levels – Zeff ~1.3;
    • An evolving brand-new glow-discharge cleaning technology.

    Carbon-I Impurity Movement

    Divertor Test w/ Ti-arc and LN2 Systems

    Inner Diverter Control

    Flared magnetic fields offer thermal protection by creating a barrier against heat transfer.

    Patterns of Reactor Lifetime and Initial Temperature

    • FRC performance increase with vacuum/wall conditioning;
    • Total temperature (ion+electron) constant increase – early Ttot up to 2 keV.

    Edge biasing/control from outer diverters – C-2U-like configuration

    Optimization Aimed at Controlling the Inner Diverter

    The effects of edge biasing and flaring diverter fields are significant in various applications. These techniques not only enhance plasma stability and performance but also improve exhaust efficiency and prolong the lifetime of fusion devices. By implementing these methods, scientists and engineers are pushing the boundaries of plasma physics and bringing us closer to achieving practical fusion energy.

    Comparison of Operating Conditions

    Outer diverter biasing (R-2U-like)

    Inner diverter w/ flaring without biasing

    Inner diverter w/ flaring and biasing

    Enhanced Efficiency as a Result of Optimisation

    Active Feedback Control

    • Studies on flux-conserver simulation;
    • Active current control of Energy Quotient (EQ) and mirror coils;
    • Trim coils with high potential to provide more control options in the near future.


    • Patent applications (HTS magnets);
    • Designed SR55 spherical reactor;
    • HTS magnet development team and laboratory;
    • Demonstration of a small tokamak SR25 1.0;
    • Demonstration of a second small tokamak with all HTS magnets.

    Milestones 2019-2021

    SR25 reactor demonstrations HTS magnet demonstrations
    First plasma Q1 2019
    15 million degrees Q3 2019
    100 million degrees Q3 2020
    Energy Gain conditions Q2 2021
    3 tesla prototype Q3 2019
    5 tesla prototype Q3 2020
    SR25 Toroidal Field magnet Q2 2021

    Progress Report

    Major Engineering Achievements and Status

    • Creation of most of the reactors within a year including the dismantling of the core;
    • Enhancement of the system's reliability and functionality with uptime exceeding 98%;
    • Successful upgrade to the tunable neutral beam.

    Key Physics Achievements and Status

    • Robust FRC formation and conversion;
    • Improved initial FRC – increased size, thermal energy, and temperature;
    • Successfully (re)produced long-lived FRCs (C-2U-like);
    • Improved FRC performance with flaring diverter magnetic fields;
    • Consistent advancement towards active feedback control, switching diverter control, and improving beam power/tunability.


    Scientific feasibility has been successfully demonstrated, showcasing the following achievements:

    • Transport scaling has been established for the collisionless regime;
    • Macroscopically stable operation has been achieved;
    • Active feedback control has been established and effectively demonstrated;
    • The capability for heating and current drive has been established and effectively demonstrated;
    • Demonstrated successful thermal insulation for open field lines, SOL (Scrape-Off Layer), and divertor.