Compact fusion · Ember-1 pilot plant

A sun that never sets.

Solstice builds high-field fusion power plants that deliver firm, carbon-free electricity around the clock, manufactured on a production line instead of poured on site.

Explore Ember-1 How it works
18:42 · Grid demand peak · Solar output falling

The sun sets.
Demand doesn't.

02:13 · Ember-1 net output 400 MWe

Firm power,
all night long.

150M °C
Core plasma temperature,
10× the core of the sun
20 T
On-coil field from REBCO
high-temperature superconductors
Q > 10
Design fusion gain:
power out vs. heating in
400 MWe
Net electric output
per Ember-class plant

// 01 — Technology

Four hard problems. One machine.

Fusion's physics has been proven for decades. The barrier is engineering: magnets strong enough to make the machine small, controls fast enough to keep plasma stable, and materials that survive a 14 MeV neutron flux. We work on all four in-house.

01 / Magnets

HTS field coils

REBCO tape wound into no-insulation coils hits 20 T at 20 K. Because fusion power scales with B⁴, doubling the field shrinks the reactor roughly 16×.

REBCO · 20 K · 20 T · 1,300 km tape/plant
02 / Control

Real-time plasma control

A learned controller running on FPGAs reads 2,400 magnetic probes and reshapes the plasma every 50 µs, suppressing disruptions before they start.

20 kHz loop · 2,400 sensors · <1% disruption rate
03 / Blanket

FLiBe breeding blanket

A molten-salt blanket absorbs neutron energy as heat and breeds its own tritium from lithium-6, so the plant is self-sufficient in fuel.

TBR 1.12 · 650 °C outlet · liquid, replaceable
04 / Conversion

sCO₂ power cycle

Supercritical CO₂ turbines turn 650 °C salt heat into electricity at 46% efficiency, with turbomachinery a tenth the size of steam equivalents.

Brayton cycle · 46% η · 10× smaller turbine

// 02 — Ember-1

A star in a box the size of a house.

Ember-1 is our pilot plant: a compact, high-field tokamak designed to be the first fusion device to put net electricity on the grid. It is under assembly now.

Live sim · Ember-1 Standby
BT
0.00
T
Te
0.0
keV
ne
0.00
10²⁰/m³
Pfus
0
MW
Q
0.0
Fusion powert = 0.000 s
ConfigurationCompact high-field tokamak
Major radius1.85 m
Toroidal field on axis12.2 T
Fusion power1,100 MW
Auxiliary heating25 MW ICRF
Net electric400 MWe
FuelDeuterium–tritium, self-bred
Footprint4 acres, including switchyard

// 03 — Manufacturing

Built like a fab, not a megaproject.

Large nuclear projects have historically run over budget because every one is built from scratch on site. We design for the opposite: standardized modules, made on a line, shipped on a truck, and bolted together in months.

  1. Coil line

    Robotic winding cells produce one 18-tonne TF coil every 9 days, with in-line quench testing at full current.

  2. Vessel modules

    Vacuum-vessel sectors are electron-beam welded and leak-checked to 10⁻⁹ mbar·L/s before they leave the factory.

  3. Truck-sized shipping

    Every module fits on a standard heavy-haul trailer. No river barges, no custom roads.

  4. Site assembly in 14 months

    Foundations go in while modules are being built, so the site stays off the critical path.

// 04 — Milestones

From magnet to megawatt.

Nine years from a test coil to electrons on the grid. Two milestones are behind us; Ember-1 is on the floor now.

  1. 2023Done

    20 T coil

    Large-bore HTS test coil reaches 20.1 T and survives a deliberate quench.

    Peak field
    20.1 T
    Quench
    No damage
  2. 2025Done

    Integrated magnet test

    Full TF sector energized with the cryoplant and power supplies in the loop.

    Scope
    Full TF sector
    In the loop
    Cryo + power
  3. 2026In progress

    Ember-1 assembly

    18 of 18 TF coils delivered. Vacuum vessel closure underway.

    TF coils
    18 / 18
    Vessel closure
    Underway
  4. 2028Next

    First plasma → Q > 1

    Commissioning campaign targeting scientific breakeven in deuterium–tritium.

    Target
    Q > 1
    Fuel
    D–T
  5. 2032Goal

    Electrons on the grid

    First commercial Ember plant delivers 400 MWe of firm power.

    Output
    400 MWe
    Power
    Firm, 24/7

// 05 — Careers

Build the last power plant humanity needs.

We hire physicists who like hardware and engineers who like physics. Small teams, real machines, and a test cell down the hall.

Plasma Control EngineerControls · Rust / FPGABoston, MA→ Superconducting Magnet EngineerMagnetsBoston, MA→ Cryogenics Systems LeadPlant SystemsDevens, MA→ Tritium Process EngineerFuel CycleDevens, MA→ High-Power RF EngineerHeating & Current DriveBoston, MA→

Power the night with us.

Utilities, offtakers and investors can request a technical briefing on Ember-1 and the commercial deployment plan.

Typical response within 2 business days