top of page

Deciphering the Lawson Criteria in the Context of Aneutronic Fusion

Deciphering the Lawson Criteria in the Context of Aneutronic Fusion

The Lawson Criteria, a seminal metric in fusion research, sets the conditions that a fusion plasma must achieve to obtain a net positive power output. As aneutronic fusion gains traction, especially with the innovative Kronos SMART approach and the emphasis on the Deuterium and 3He reaction, it's crucial to understand how this fundamental criterion applies.

1. The Basics of the Lawson Criteria:

Introduced by John D. Lawson in 1957, the Lawson Criteria stipulates that for fusion to be a viable power source, the product of the plasma density (n) and the confinement time (τ) must exceed a certain threshold[15]. Mathematically:

This relationship ensures that more energy is produced from fusion reactions than the energy lost due to various mechanisms, like radiation and particle losses.

2. Aneutronic Fusion and its Distinctive Traits:

Aneutronic fusion reactions produce energy without or with minimal neutron emissions. The Deuterium and 3He reaction is a primary example, producing helium and a proton, but no neutron. Such reactions have the benefit of reduced radiation and fewer activation products[12].

3. Lawson Criteria in Aneutronic Fusion:

Higher Threshold: Due to the absence of neutrons, which carry a significant portion of the energy in conventional fusion, aneutronic fusion often requires higher plasma densities and confinement times to be viable[12].

Temperature Sensitivity: The Deuterium and 3He reaction has a specific temperature window for optimal performance. Thus, while fulfilling the Lawson Criteria, maintaining this temperature is crucial for efficient energy production.

4. Kronos SMART and the Lawson Criteria:

Advanced Confinement: Kronos SMART employs cutting-edge techniques to ensure that the plasma confinement time is maximized, aligning with the stringent demands of aneutronic fusion.

Optimized Plasma Conditions: Kronos SMART designs its reactors to maintain the precise plasma conditions, ensuring that the Deuterium and 3He reaction remains within its optimal temperature window, while also meeting the Lawson Criteria.

5. Evolution of the Lawson Criteria:

While the original criteria were based on neutronic fusion reactions, advancements in understanding have led to modified criteria for aneutronic reactions[12]. These consider not only the density and confinement time but also factors like alpha particle heating, which is crucial for the Deuterium and 3He reaction.

6. Implications for Future Reactor Designs:

Meeting the Lawson Criteria for aneutronic fusion is more challenging but offers significant benefits, especially in terms of reduced radiation hazards. Kronos SMART’s focus on the Deuterium and 3He reaction, backed by its advanced design, exemplifies how modern reactors can overcome these challenges.


The Lawson Criteria, while established for traditional fusion reactions, remains a vital benchmark for aneutronic fusion. Kronos SMART's dedication to achieving and surpassing these criteria, especially for the Deuterium and 3He reaction, promises a future where fusion energy is not just a possibility, but a sustainable and efficient reality.


[12] R. G. Mills, "Lawson Criteria," IEEE Trans. Nucl. Sci. 18, 205 (1971).

[15] J. D. Lawson, "Some Criteria For a Power Producing Thermonuclear Reactor," Proc. Phys. Soc. B, 70, 6 (1957).

bottom of page