Exploring Aneutronic Fusion Reactions Beyond Deuterium and 3He

Aneutronic fusion, as the name suggests, is a fusion reaction with negligible or no neutron production, which can mitigate many of the challenges associated with traditional fusion. While Deuterium and 3He are at the forefront of aneutronic fusion research, especially within the framework of Kronos SMART, several other isotopes also hold potential for aneutronic fusion. This study seeks to shed light on these isotopes, assessing their viability and associated challenges.

1. The Appeal of Aneutronic Fusion:

Before diving into alternate isotopes, it's essential to understand the attraction of aneutronic fusion:

Reduced Radiation: Aneutronic fusion reactions produce substantially fewer neutrons, reducing the risk of material activation and radiation-related challenges[13].

Direct Energy Conversion: These reactions can potentially allow for direct conversion of fusion energy to electricity, enhancing overall system efficiency.

2. Beyond Deuterium and 3He: Other Potential Aneutronic Fusion Reactions:

Deuterium - 6Lithium Reaction:
Reaction: 2D+6Li→24He+22.4MeV2D+6Li→24He+22.4MeV
Pros: High energy yield per reaction and an abundance of lithium as a fusion fuel.
Cons: Lithium, when exposed to high temperatures, can breed tritium, introducing neutronic reactions[1].
Proton - 6Lithium Reaction:
Reaction: 1p+6Li→4He+3He+4.0MeV1p+6Li→4He+3He+4.0MeV
Pros: Relatively simple fuel sources.
Cons: Lower energy yield compared to the Deuterium - 3He reaction[13].
3He – 6Lithium Reaction:
Reaction: 3He+6Li→24He+1p+16.9MeV3He+6Li→24He+1p+16.9MeV
Pros: High energy yield.
Cons: 3He scarcity might pose challenges[14].
Proton – Boron-11 Reaction:
Reaction: 1p+11B→34He+8.7MeV1p+11B→34He+8.7MeV
Pros: Boron is abundant, and the reaction is purely aneutronic.
Cons: Requires extremely high temperatures for ignition, making it challenging to achieve[13].

3. Challenges in Harnessing Alternate Aneutronic Reactions:

Fuel Scarcity: Some fuels, like 3He, are scarce on Earth, making it a less viable long-term solution unless effective mining solutions are devised, such as lunar mining[14].

Reaction Conditions: Some reactions, despite being aneutronic, demand stringent conditions, including extreme temperatures or pressures, which can pose technical challenges[1].

Fuel Handling: Some fuels, especially those involving lithium, can introduce complications in handling and containment, due to potential tritium production or other chemical challenges[13].

Conclusion:

While Deuterium and 3He are currently the most explored isotopes for aneutronic fusion, especially in projects like Kronos SMART, the fusion horizon is vast. Other isotopes, such as lithium or boron, hold potential, even though they come with their unique sets of challenges. Understanding these potential isotopes and the hurdles they present will pave the way for a more comprehensive approach to aneutronic fusion research.

References:

[1] C. Baccou et al., "New Scheme to Produce Aneutronic Fusion Reactions by Laser-Accelerated Ions," Laser Part. Beams 33, 117 (2015).

[13] B. Nayak, "Reactivities of Neutronic and Aneutronic Fusion Fuels," Ann. Nucl. Energy 60, 73 (2013).