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Direct fusion drive

Explainer video

The inside of the DFD engine nuclear engine
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The Direct Fusion Drive (DFD) is a compact nuclear fusion engine which could provide both thrust and electrical power for spaceships. This technology opens unprecedented possibilities to explore the solar system in a limited amount of time and with a very high payload to propellant masses ratio.

This engine is attractive for long missions where a lower thrust version of the engine, having a propellant mass ratio near unity, provides efficiencies that other engines cannot achieve.

Designed to produce both thrust and electric power for interplanetary spacecraft

Long-term source of acceleration with self-sustaining fuel supply. Modelling shows that this technology can potentially propel a spacecraft with a mass of about 1,000 kg (2,200 lb) to Pluto in 4 years.

Since DFD provides power as well as propulsion in one integrated device, it would also provide as much as 2 MW of power to the payloads upon arrival. Designers think that this technology can radically expand the science capability of planetary missions.

The Direct Fusion Drive nuclear engine

Both propulsion and a sustainable, low-risk, available source of energy

Production description

The Direct Fusion Drive is a revolutionary steady state fusion propulsion concept, based on a compact fusion reactor. It will provide power of the order of units of MW, providing both thrust of the order of 10−101N with specific impulses between 10,000 – 15,000 seconds and auxiliary power to the space system.

Forecasted statistics

Thrust (N)
10 - 101
D - 3He
Exhaust Speeds (km/s)
110 - 350
Dimensions (m)
9.8 x 3.5 x 3.5


Pulsar Fusion is presently committed to the construction of its initial prototype static fusion rocket engine. After completing a State of the Art (SoA) assessment on heating technology in 2021, further analysis was carried out by a panel of experts to finally make an informed decision on an initial design point for the system.

Pulsar has now proceeded to phase 3, the manufacture of the initial test unit. Static tests are to begin in 2024 followed by an In Orbit Demonstration (IOD) of the technology in 2027.

Diagram of how the Direct Fusion Drive works

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Meet the UK’s leading fusion company