Horne Technologies Developing Superconducting IEC Fusion Device

Horne Technologies has built a superconducting inertial electrostatic confinement (IEC) fusion device which it hopes will help enable it to achieve net power in the 2020 timeframe. The company claims that its system is the world’s first superconducting, high beta-style plasma research device in operation.

“The first superconducting device was very economical due to the commercial availability of wire and the technical capability of Horne Technologies,” said Tanner Horne, Founder of Horne Technologies. “The entire enterprise has been funded privately.

“While there are many groups now pursuing fusion, the closest competitors to this technology are EMC2’s Polywell and Lockheed Martin’s Compact Fusion. However, no other group has yet demonstrated an operational superconducting prototype. Horne Technologies first demonstrated a superconducting prototype in 2017.”

0.5 T Prototype Device Deploys SC REBCO Wire

Horne Technologies’ first generation prototype system uses REBCO superconducting wire in 0.5 T coils to contain the reactor plasma. The coils are cooled with liquid nitrogen and the system is capable of operating at a pressures between 1 ´ 10-8 and 1 Torr. The system relies on a 3 A current.

“We looked at a number of commercial suppliers for the REBCO wire and ultimately made the decision based on lead time,” said Horne. “Many suppliers are seeing increased lead times in the last few years.

“Two superconducting coils are used in the first-generation prototype. Each of these coils has nearly 30 meters of HTS wire and the capacity to handle up to 30 A in field. The system performed surprisingly well, demonstrating the use of these new superconducting materials and validating the technology that will be utilized in the next generation devices.”

Horne Technologies Seeks to Scale Up Prototype

Horne Technologies is seeking to scale up its device and demonstrate it to be the world’s most efficient fusion device. A planned second generation device will have an improved coil structure, advanced cryogenic cooling, and operate in a 4 ft ´ 6 ft vacuum chamber. The device will be used for final validation of all the required technologies and as a proof of concept.

“Liquid nitrogen will be used for [the second generation device] for initial testing then we will be switching to another, proprietary cryogen,” said Horne. “The coil structure will have an entirely new design for its supports and new implementation. We will be testing multiple coil configurations and use this information to optimize the device.

“The second generation system will have a working volume 6000% larger than the first generation system. The new device is being designed to utilize around 32,000 A of current and capability of operation up to 1 billion degrees Kelvin. Currently, our new large chamber is being fitted for the experimental setup, with the goal of first plasma in early 2019.”

IEC Allows for use of Aneutronic Fuel

Horne Technologies, based in Louisville, CO, has been working for 10 years to develop a viable fusion reactor for use in space and on Earth that emits minimal amounts of radiation. The company has focused on IEC fusion devices because they may allow for the use of aneutronic or advanced fuel.

“Aneutronic fuel releases much less neutronic radiation, only a few percent, and the energy can be converted directly into electricity,” said Horne. “The disadvantage is that it is orders of magnitude more difficult than the easiest reactions, which themselves have not yet even been successful for energy production. The advantage of designing for future compatibility with aneutronic fuel is that the same technology can be used for the easier reactions.”

In an IEC reactor, which operates in a vacuum chamber, fusion materials are accelerated to the center of the reactor using electrostatic attraction. As the materials are attracted to the center, they accelerate to high energies and then collide to produce fusion.

IEC Device has High-beta Fusion Core

The company’s design uses superconducting magnets as the IEC grid to reduce the collisions of the accelerated fuel into the grid. This is possible because the strong magnetic field causes the charged ion fuel to be diverted around it as it is being attracted to the grid.

An important advantage of using a magnetically-shielded grid is that it allows for a magnet configuration that sets up a high-beta fusion core. This is a condition where the plasma pushes back against the field, causing a plugging effect to the leaks and creating an empty field region where the plasma is momentarily contained. This momentary containment increases the chance fusion will occur.

This plasma containment region also offers another optimization benefit to the system: if the plasma is biased with electrons, it will build up a potential well. The center region will act like a virtual grid, causing even less ions to run into the magnetically-shielded grid and improving the efficiency further.

“The efficiency of both the IEC-style reactors and MCF reactors are historically low,” added Horne. “Utilizing a hybrid approach with the technology of both we hope to increase the efficiency to demonstrate the feasibility of the technology for energy production.”

Ion Collision Rate must be Improved for Reactor to Produce Energy

A problem with the IEC is that ions at times miss each other and are shot back out of the center and lost from the system. Such ions must be slowed down and turned around so that they once again accelerate towards the center of the reactor. Horne Technologies is working to improve the recirculation of ions in its device.

“Recirculation can be improved by geometric configuration of the coils,” said Horne. “Multiple configurations will be experimented with in the second generation device.”

Another issue is that many of the fuel ions that are accelerated into the IEC center actually miss each other and do not collide to fuse. If they miss, they have to make the loop again for another try. If the super-hot, fast ions could be held in the same place for a longer period of time then they would have a higher chance of fusing. The style of high-beta confinement is used to help achieve this.

“Rather than thinking in terms of a set fusion rate we are more interested in the efficiency of the device,” said Horne. “For each watt of power input, what is the fusion rate achieved? This drives the research rather than the ultimate reaction rate.

“Conditions that lend themselves to high rates may not be conducive to high efficiency. Once high efficiency appears possible, then scaling will be looked at for the third generation device.”

Net Energy Generation Possible as soon as 2020

Horne said that the date at which net energy can be realized will depend on the scale required: “We hope to have the knowledge to reach scientific net energy after the experimentation of the second-generation device, which is scheduled to be complete before 2020. If the results show it can be achieved within a similar scale then we would expect 6 to 8 months implement.

“If the scale is required to be significantly larger it would likely take longer. The key technologies [we seek to develop] are IEC heating, a magnetically-shielded grid, a high-beta reaction core, and a proprietary method to mitigate hot ions from losing their energy to cold gas in the chamber.”

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