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Nuclear Fusion: Should we bother? Critique and debate

By Peter Catalano – with additional commentary by Eric J. Lerner, President and Chief Scientist LPPFusion, Inc., Middlesex, NJ – LPPFusion.com

A press release issued by the Global Warming Policy Foundation (GWPF) on 29 January argues that “nuclear fusion is unlikely to be a decarbonisation saviour, at least not in the short-to-medium term.” 

The GWPF press release was based on a briefing by retired nuclear researcher John Carr, PhD called Nuclear Fusion: Should we bother?

In chapter 6 of his briefing, “Alternatives To Mainstream Fusion”, Carr commented on research programs at a company called TAE whose corporate mission is to build an aneutronic nuclear fusion device. The goal for such a device is to power electric energy grids without creating any contaminating radioactivity in the process. Aneutronic fusion energy devices use a Hydrogen-Boron fuel known in the trade as pB-11.

Here Dr. Carr claimed:

“…the snag is that this fuel [pB-11] requires six times the reaction temperature of D-T (> 1 billion degrees). Critically, the radiation losses in the plasma are higher, to the point where an energy gain is impossible, according to calculations. It is surprising that this company [TAE], which has prospered for 25 years, is advocating a technology that many experts say can never work. ([1])

First off, Carr’s blanket claim that aneutronic fusion “can never work” is not true. Not only is the temperature criterion for aneutronic fusion possible to achieve, but the fact is, this milestone has been reached AND exceeded years ago by a small US company called LPPFusion. (LPPFusion is listed in the IAEC reference in Carr’s brief.)

A 2017 peer-reviewed article in Physics of Plasmas titled, “Confined ion energy >200 keV and increased fusion yield in a DPF with monolithic tungsten electrodes and pre-ionization”, reported that the LPPFusion experimental device called FF-1 using Deuterium- Deuterium fuel:  

 “…produced a new single-shot record of 240  +/- 20 keV for mean ion energy, a record for any confined fusion plasma.” ([2])

(Note: 240 keV equates to well over 2 billion degrees Kelvin. The center of the sun is 10 million K.)

These results were achieved without pB-11 fuel. In recent years, LPPFusion has continued development with their experimental device and expects to introduce pB-11 fuel later this year. LPPFusion uses a device known as the Dense Plasma Focus. This approach is radically different from mainstream magnetic confinement or from inertial confinement devices. ([3],[4],[5])

Furthermore many researchers have made some important strides toward practical aneutronic fusion, as Eric Lerner comments below:

In reporting on such a rapidly developing field as fusion energy, John Carr relies exclusively on research done more than 26 years ago, which was when the papers he cites about the feasibility of pB-11 fusion were published. Things have changed a lot since then and those conclusions—that pB-11 fusion is impossible– have been invalidated. You can get a good summary review with recent references from our own recently-published paper “What are the fastest routes to fusion?” in the special collection of private fusion research in Physics of Plasmas.

I quote from that peer-reviewed paper, in italics, here replacing the references with links to the papers cited:

“However, subsequent research showed that this analysis [cited by Carr] was faulty for several reasons. First, it rested on reaction cross sections and reaction rates that were more than a factor of 2 too low.”

Of course, that alone invalidated the analysis, since even doubling the fusion power in the calculations made it clear that pB11 could produce more fusion energy than radiation, thus achieving ignition.

“Second, it assumed that there was no way to maintain, for the duration of a fusion burn, a large gap between electron and ion temperatures, which would decrease bremsstrahlung emission.”

This also turned out to be another invalid claim which Carr relies on to assert that an aneutronic fusion device is an impossibility. LPPFusion’s own research demonstrated that at high magnetic fields, the quantum magnetic field effect would produce Ti > 25 Te. This effect, first pointed out in the 1970’s, and studied in the case of neutron stars, involves the reduction of energy transfer from ions to electrons in the presence of a strong magnetic field.

“In addition, other work by TAE, a private fusion company, showed in simulations that ion beams in field-reversed configuration (FRC) devices could reach net energy conditions without substantial heating of electrons. HB11, and Marvel Fusion, additional fusion companies, have shown the same for side-on laser irradiation approaches. These calculations demonstrated that net energy production with pB-11 was physically possible. Among other effects, they noted that heating of ions by fusion-produced alpha particles could be faster than the heating of electrons.”

While it is correct that pB-11 requires higher temperatures than D-T, LPPFusion already  demonstrated in 2017 confined ion energy in excess of 200 KeV. At the high densities expected with optimized performance of the FF-2B device, fusion burn of pB11 fuel will increase Ti to >600KeV, according to simulations.

Thus, over the quarter century since the conclusions that Carr cites were published, the theoretical feasibility of pB-11 fusion to achieve ignition and net energy has been abundantly demonstrated. No one says it is easy to get net energy with pB11 or any fusion fuel. But it is clearly possible. Now at least four companies, including ours, are trying to do it.

Meanwhile it’s no great news that prospects are dim for commercialized laser-based or tokamak fusion devices, in general, and with the ITER project, in particular. Long ago former DOE Fusion Director Robert Hirsch discounted much possibility for commercializing nuclear fusion energy devices using a tokamak configuration ([6],[7]).

But that doesn’t mean nuclear fusion energy has no future. In 2021 a panel of esteemed physicists and nuclear power engineers were invited to evaluate research efforts at LPPFusion including Robert Hirsch. Their report states:

“One point that became clear to the committee is that the LPPFusion program …merits a much higher funding level…” [8]


[1] Nuclear Fusion: Should we bother? The Global Warming Policy Foundation Briefing 66, p.15 https://www.thegwpf.org/content/uploads/2024/01/Carr-Nuclear-Fusion.pdf

[2] Confined ion energy >200 keV and increased fusion yield in a DPF with monolithic tungsten electrodes and pre-ionization, Eric Lerner et al,Physics of Plasmas https://pubs.aip.org/aip/pop/article/24/10/102708/795184/Confined-ion-energy-gt-200-keV-and-increased

[3] Eric Lerner explains the basis for the dense plasma focus configuration of his fusion energy device and how it works in this video

https://www.youtube.com/watch?v=e4WJdkHmq64&list=PLBg1fqjrUVrmiSM2Qr0GM0c8XyDx15lGP&index=3

[4] a complete suite a videos explaining a neutronic fusion can be found at this YouTube playlist

[5] the complete bibliography of Eric Lerner’s scientific publications can be found at https://www.lppfusion.com/peer-reviewed-papers/

[6] Fusion Research: Time to Set a New Path; Hirsch, Robert L, Issues in Science and Technology, Vol.XXXI, No4, Summer 2015

[7] Necessary and sufficient conditions for practical fusion power, Hirsch, Robert L in Physics Today, Vol.70, Issue 10, 1 Oct 2017 https://pubs.aip.org/physicstoday/article/70/10/11/910381/Necessary-and-sufficient-conditions-for-practical

[8] Evaluation Of LPPFusion Dense Plasma Focus Research https://www.lppfusion.com/technology/focus-fusion-energy/dpf-device/evaluation-of-lppfusion-dense-plasma-focus-research/


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Dr John Carr responds

The objections to my paper from Peter Catalano and Eric Lerner are related to the part about proton-Boron (p-B11) fusion and in particular the sentence: “It is surprising that this [TAE] company, which has prospered for 25 years, is advocating a technology that many experts say can never work”. In the context of the paper it should be clear that “work” means “operate a commercial fusion power plant”. Part of the objection is that the only reference on this issue in my paper is the book by Parisi & Ball which in turn references  Rider.

A page on my website includes more details on this problem than was possible in my paper. The essential details on this page are as follows:

The massive drawback for p-B11 fuel is Bremsstrahlung(a.k.a. “braking” or deceleration radiation). The energy balance in fusion is well explained in the blog of Nick Hawker: Why does fusion need to be so hot? which gives a clear presentation of the dilemma for aneutronic fusion. To achieve net fusion power output the power generated by fusion must be greater than the power lost by radiation. For p-B11 fuel,  the electric charge for boron is 5 units compared to 1 for tritium so that the Bremsstrahlung radiation in the plasma is much higher to the point where the fusion power is never greater than the power lost by radiation. 

The paper of Nevis (A Review of Confinement Requirements for Advanced Fuels) concludes that ignition is impossible in p-B11. The paper of Putvinski, Ryutov and Yushmanov of TAE Technologies (Fusion reactivity of the pB11 plasma revisited) makes new calculations with updated cross-section, but concludes that while ignition is still marginal, p-B11 remains a viable fusion fuel.

From these publications it is clear that many, but not all, experts conclude that making a p-B power plant is impossible or nigh impossible.

—————–

Peter Catalano and Eric Lerner reply

Let’s make clear what is at issue here. In order to achieve nuclear fusion, an electrically-conducting gas called a plasma must be heated to immense temperatures. To get more energy out of the device than is put in, it is necessary to reach “ignition”, which is the condition in which the rate that fusion energy is produced in the plasma exceeds all energy losses from the plasma, and the plasma starts to heat itself up very fast. The hotter it gets, the more fusion energy is generated.

The “bremsstrahlung radiation” or in English,  a “braking” radiation, which Dr. Carr refers to, is a major way in which a plasma loses energy, cooling it down. The hot electrons in the plasma radiate this energy when they collide with the nuclei. Dr. Carr is arguing that, under all conditions, the rate that this bremsstrahlung radiation is produced will exceed the rate that fusion energy is produced in a pB11 plasma, so ignition can’t be achieved.

But Dr. Carr is ignoring the central point of our reply, which is based on the fact that ALL the calculations that he, and those he cites, rely on to show the “impossibility “ of ignition in pB11 fusion were performed in the 20th century. Our point is that these calculations have been proven to be wrong by subsequent research in the present century.  The correct formulation is “Some researchers argued in the 20th century that pB11 fusion is impossible. However, their calculations were shown to be mistaken by more recent work.”

Specifically, the secondary sources cited by John Carr (Nick Hawker and Parisi & Ball)  allrely onthe calculations performed by Rider in 1995. (Rider, T. H. (1995). Fundamental limitations on plasma fusion systems not in thermodynamic equilibrium (PhD thesis). MIT. p. 25. hdl:1721.1/11412.) Nevins’ 1998 paper also relies on Rider’s earlier work. None of the sources Dr. Carr cites for “impossibility” are based on calculations done in the present century.

The 20th century calculations that Dr. Carr  uses to make his case were wrong in two basic ways. They underestimated the rate of production of fusion energy that the pB11 reactions produced because they were based on  measurements that turned out to be wrong. Fusion reaction rates are calculated from reaction “cross sections” that are measured in particle accelerator experiments. These are not easy to perform accurately.

Better techniques in the 21st century allowed more accurate measurements. The two charts below give an idea of the big change in cross section values from the ones the 20th century calculations relied on (left) and the much more accurate 21st century ones(right) from this 2016 paper: https://link.springer.com/article/10.1007/s10894-016-0069-y

Note the much higher peaks in the more recent, and far more accurate data.

Since Rider, whom Carr relies on, had measurements that were less than half the correct ones, he underestimated the fusion energy from pB11 by more than a factor of two, wrongly concluding that the Bremsstrahlung radiation would be more than the fusion energy produced, so the plasma would always cool off.

Second, Rider did not take into account effects that would reduce the electron temperature and thus reduce the bremsstrahlung radiation, so he overestimated that radiation. There are several effects that reduce the electron temperature, and they were published in peer-reviewed papers by LPPFusion in 2005 and later in 2011, by HB11 in 2017 and by TAE in 2019. These effects reduce the bremsstrahlung radiation by as much as a factor of 5.

As LPPFusion prepares to introduce the pB-11 into the company fusion energy device later this year, several strategies will be utilized to take advantage of effects that can be used to offset any potential cooling from Bremsstrahlung radiation.

Thus, today in 2024, the current theoretical calculations based on the correct measurements and taking into account the relevant physical processes agree that in the right conditions, fusion energy production will well exceed bremsstrahlung radiation and thus ignition and net energy production with pB11 is possible.

Short summary—in the 21st century, practical pB11 fusion energy is theoretically possible. The earlier calculations that Dr. Carr relies on were simply wrong. Given pB11 fusion’s enormous advantages for cheap, clean, safe and unlimited energy, we need to try to get it done.


John Carr replies

The objection in the original complaint from LPP Fusion is the sentence in the article: “It is surprising that this company [TAE ], which has prospered for 25 years, is advocating a technology that many experts say can never work.” The issue in this can be simply answered by looking at the list of private companies in the table below. In 25 companies which had accumulated funding >$5 million in 2023, 5 use proton-boron fuel while 20 do not. Given the advantages of proton-boron fuel compared to deuterium-tritium fuels, it is clear that 21 companies have numerous experts who believe the technology cannot work. This proves the phrase “many experts say can never work” is true. Furthermore, the fact that the second largest aneutronic fusion company, HELION, is proposing to use D-He3 rather than p-B11, obviously means many experts there think that p-B11 will never work.

Another point is the long LPP Fusion correspondence is the sentence, “Critically, the radiation losses in the plasma are higher, to the point where an energy gain is impossible according to calculations” [Jason Parisi and Justin Ball, ‘Future of Fusion Energy’, World Scientific, 2018]. Here the LPP Fusion point is that the calculations in the reference are too old and did not consider updates to p-B cross-sections. The book was written in 2018 and so is not old and very likely does use the latest cross-sections, hence negating the objections of LPP Fusion. The blog of Nick Hawker, which was cited in my previous reply to reinforce the information in the book of Parisi and Bell, is even more recent, being from last year, and so again the criticism does not fit.

The article by Edwin Cartlidge: Proton–boron fusion passes scientific milestone – Physics World, gives an up-to-date review of the situation of proton-boron fusion research, including opinions of many fusion experts.