Cold fusion

from Wikipedia, the free encyclopedia

As cold fusion refers to methods usable as an energy source controlled nuclear fusion of hydrogen isotopes are intended to produce and to no thermonuclear reaction , so no plasma with high temperature and density , need. This distinguishes cold fusion from the processes that are used in nuclear fusion reactors or inertial fusion . A commonly used synonym for cold fusion is LENR ( low energy nuclear reactions , so nuclear reactions at low energy).

The first considerations about fusion at low temperatures came in the 1940s in the Soviet Union ( muon- catalyzed fusion). The term became known cold fusion (English coldfusion ) by 1989 by chemists Stanley Pons and Martin Fleischmann imagined experiment. They claimed to have carried out an electrochemical nuclear fusion on a palladium electrode at 300 K (27 ° C). This briefly gave rise to hope that a new, practically inexhaustible option for generating and supplying electricity had been found. However, the laboratory results of Pons and Fleischmann could not be confirmed by independent third parties. A commission set up by the United States Department of Energy came to the conclusion that it was pathological science . As a consequence, most scientists assume that a nuclear reaction with a significant release of energy cannot be initiated in this way.

Proposed working mechanisms

Muon Catalyzed Fusion

In the late 1940s, Frederick Charles Frank and Andrei Sacharow considered this. They postulated based on theoretical approaches that muons could facilitate the initiation of fusion nuclear reactions in the manner of a catalyst . In 1948 Sakharov coined the term "cold fusion" for it. Luis W. Alvarez , who was awarded the Nobel Prize in Physics in 1968 , discovered unusual traces on bubble chamber recordings in 1956 . Together with Edward Teller , he came to the conclusion that muons had triggered nuclear fusions.

Wenedikt Petrovich Dschelepow found out in the mid-1960s at the Nuclear Research Institute in Dubna that the number of muon-catalyzed fusions in deuterium increases with increasing temperature. Soon afterwards, in 1967, the then student EA Wesman (who worked with Semjon Solomonowitsch Gerschtein ) provided an explanation through resonances with more complicated molecular configurations (such as three deuterons with both muonic and electronic bonds). In 1975 Leonid Ivanovich Ponomarjow , who was a leader in the Soviet Union in the ever more accurate calculation of the energy levels of such mesonic molecules, found a particularly strong resonance effect in deuterium-tritium molecules. The effect could be confirmed in Dubna 1979 by Jelepov, which contributed to the revival of the interest in muon-catalyzed fusion also in the west (especially Steven Jones in Los Alamos).

According to a result from atomic physics, the orbit radius of a muon around an atomic nucleus is inversely proportional to the reduced mass of the atomic nucleus and the muon. Since a muon has a much higher mass than an electron , its orbital is much closer to the atomic nucleus than an electron. Since the mass of the atomic nucleus is also included in the reduced mass, a higher mass of the atomic nucleus also leads to a denser orbital of the bound particle. If a negatively charged muon hits a DT molecule (made up of a deuterium and a tritium atom ), it can happen that the muon displaces an electron from the molecular orbitals and forms a new molecular orbital. Due to the close shielding of the charge of the tritium nucleus by the muon, the atomic nuclei are bound around 200 times more tightly than with the original molecule. Therefore, nuclear fusion can occur comparatively easily, as a result of which a muonic helium-5 atom is created from the muonic DT molecule . This decays with a probability of 99.4% into a helium-4 atom, a muon and a neutron, whereby energy is released:

After this reaction, the released muon can trigger the same reaction again and thus keep a fusion process going like a chain reaction . The muon acts like a chemical catalyst . With a probability of 0.6% but the muon remains in the helium-4 atom stick (Engl. Sticking and then is no longer for more merger activity only):

The entire cycle from muon capture to fusion takes about 10 −9  s. The short lifespan of the muon of around 2.2 µs thus limits the number of catalyzed individual reactions in principle to around 2000. The muon then decays again according to:

Around 3 GeV are required to produce a muon with a particle accelerator . A net energy production by injecting the generated muons into a deuterium-tritium gas mixture initially appeared possible. The fact that this is still not the case is due to the second subsequent process described above, in which the muon remains attached and thus cannot catalyze any further fusion reactions. Due to the second process, according to the laws of probability, the average number of catalyzed fusions is reduced to . The result of this geometric series is . With this lower number of fusions, only 2.9 GeV fusion energy is generated, i.e. less than is necessary to produce a new muon. Therefore, on a statistical average, no useful energy can be obtained with this process, especially if the additional electrical energy is taken into account, which is required for the manufacture and basic operation of the particle accelerator.

Metal catalytic fusion

Palladium has the highest absorption capacity of all elements for hydrogen; it can bind 900 times its own volume at room temperature. Palladium also has catalytic properties. Many attempts at cold fusion therefore use palladium.

Paneth (1926)

The first report on the conversion of hydrogen into helium in connection with palladium comes from Fritz Paneth in 1926 . During the heating of hydrogen-treated palladium preparations, he found an inexplicable amount of helium. In the following year, however, some sources of error were recognized. One example is the better permeability of glass for helium at higher temperatures. In a publication from 1927, Paneth and other authors interpreted helium as a consequence of these causes.

“Cold fusion” according to Fleischmann and Pons

Schematic experimental setup for electrochemical cold fusion

The term “cold fusion” became known through an attempt by Fleischmann and Pons that was initially reported to be a success. On March 23, 1989, Martin Fleischmann and Stanley Pons reported at a press conference on experiments in which they had observed cold fusion. These reports were received as a sensation, because it would be easy to release energy from heavy water. For a short time there was hope in the professional world that this could be made usable on an industrial scale as a practically inexhaustible source of energy.

In this experiment, the fusion of hydrogen isotopes to protium , deuterium and tritium during the electrolysis of an electrolyte on the surface of a palladium - cathode have occurred. Evidence of a cold fusion is the evidence of the resulting helium atoms, tritium and neutron or gamma rays (certain energy or frequency) as well as evidence of excess heat production that cannot be explained by chemical processes.

As early as May 1, 1989, the physicists Steven Koonin , Nathan Lewis, and Charles Barnes from Caltech demonstrated errors in the Fleischmann-Pons experiments and refuted their results at a meeting of the American Physical Society . Other laboratories did not succeed in confirming the Fleischmann-Pons results either, not even with measuring devices that were orders of magnitude more sensitive. Fleischmann and Pons themselves could not repeat their results in front of witnesses.

Meanwhile worldwide research had started. So was z. B. in July 1989 by an Indian research group of the BARC ( PK Iyengar and M. Srinivasan) and in October 1989 by a US American group ( Bockris et al .) Reported on the formation of tritium. In December 1990, Richard Oriani of the University of Minnesota reported excess heat in cold fusion experiments.

The American government set up a commission from the Department of Energy (DOE) to investigate the possible effects on national energy supplies. The DOE commission came to the conclusion in November 1989 that the current evidence of the discovery of a new nuclear process called "cold fusion" was not convincing .

The euphoria initially built up within a few months, followed by disappointment, was widely reported in the general media.

Another publication by Fleischmann contributed to the fact that the DOE took up the matter again in the years after 2003. Despite the more advanced technology of calorimetric measurement since 1989 and the follow-up experiments carried out, the DOE comes to the same result as in 1989 and advises against targeted funding for research into the effects described for the development of an alternative energy source .

In November 2005 an article appeared in the university newspaper of the TU Berlin , in which it is said that TU scientists working with nuclear physicist Armin Huke had found the first experimental evidence for the “miracles” of cold fusion in accelerator experiments in nuclear physics . The Faculty of Physics distanced itself shortly afterwards and stated that there was no comprehensive work on cold fusion at the TU Berlin.

Research work

Around the world, some research groups are still conducting scientific studies in the field of “cold fusion” or LENR, sometimes with new approaches.

Journalists occasionally deal with the topic or report on scientists who see potential in cold fusion. The American Physical Society regularly allows symposia on LENR; the American Chemical Society did this again in 2007 for the first time after 1989. In March 2012, LENR was reported at a conference of the American Nuclear Society (ANS). Peer-reviewed articles on the topic are also published. The US military authority SPAWAR (Space and Naval Warfare Systems Command) has sponsored LENR experiments since 1989. Several authors thanked SPAWAR for their support. In addition, ENEA and SRI International deal with the subject of LENR.

The University of Missouri received $ 5.5 million in research funding from a private foundation in 2012 to study the generation of excess heat in interactions between hydrogen and palladium, nickel, or platinum.

The University of Gothenburg , under the direction of Leif Holmlid, is researching laser-induced muon-catalyzed fusion reactions in high-density deuterium ( Rydberg state ). In 2015 Holmlid reported in several papers on observations of emitted heavy, neutral particles with energies above 10 MeV u −1 .

At the end of May 2019, the science journal Nature published a report by a research group compiled and funded by Google . The researchers couldn't find any evidence of cold fusion. Not having achieved some of the terms considered most favorable to the merger, they still advocate further investigation.


Seth Putterman of the University of California and his coworkers Naranjo and Gimzewski published a paper on pyroelectrically induced nuclear fusion in Nature in 2005. They present a comparatively small piece of equipment "on the laboratory bench" that enables the fusion of deuterium nuclei . To ionize deuterium atoms and then accelerate them to the speed required for fusion, the researchers used a pyroelectric crystal as the voltage source - hence the term pyrofusion . The deuterium is ionized by the strong electric field at a tungsten tip and the ions are accelerated. The neutron flux generated was 400 times the natural neutron radiation. The experimenters suspect that the source of the neutrons is the fusion of two deuterium nuclei to form helium, which creates a free neutron:

D + D → 3 He (820 keV) + n (2.45 MeV)

Because the power is limited in principle to small particle flows, there is no possibility of being able to release energy for practical purposes in this way. The setup is nevertheless suitable as a neutron source, for example for analysis purposes.


Sonofusion device used by Rusi Taleyarkhan.

The US scientist Rusi P. Taleyarkhan of the Oak Ridge National Laboratory reported in the magazine Science in March 2002 about the possibility of bringing about a controlled fusion with cavitation triggered by sound waves . This process, known as sonofusion or bubble fusion, is supposed to generate high temperatures, pressures, radiation and neutron densities that enable nuclear fusion.

A commission of five universities set up at the instigation of the US Navy came to the conclusion that experiments by another group, which seemed to confirm the results, were falsified. In August 2008, Taleyarkhan was revoked from Purdue University for unscientific conduct ( scientific misconduct ). He remains a member of the faculty, but under the designation special graduate faculty and without the right to supervise doctoral students. The affair came to be known as bubblegate .

In Germany, the Sonofusion was propagated by Günter Lohnert , University of Stuttgart; Lohnert, who also deals with pebble bed reactors , described the sonofusion as proven back in 2005. As the editor of the journal Nuclear Engineering and Design (NED), Lohnert also accepted, after only a brief examination, without consulting other reviewers, the aforementioned work, which had meanwhile been evaluated as falsified and which seemed to confirm the sonofusion. During the US investigation into Sonofusion Taleyarkhan in 2007 and 2008 he gave the opportunity to present his position in NED. In 2009, Lohnert was replaced as an active publisher by NED.

Controversial nickel-hydrogen reaction

At the beginning of 2011, the Italian entrepreneur Andrea Rossi, together with the physicist Sergio Focardi (1932-2013), claimed that he would fuse nickel and hydrogen to form copper and thus generate a self-sustaining exothermic reaction in a device known as the "E-Cat" could. Corresponding patent claims had already been denied by the European Patent Office in 2010 about the necessary inventive step . Independent confirmations of the experiment are not yet available. The gamma radiation that would actually be expected in such fusion reactions was not observed. Rossi does not allow a thorough examination of the device. Several experts therefore refrained from making a final assessment. LENR blogger Krivit has compiled evidence that Rossi systematically manipulates the device to give the impression of significant energy production.

The presentation of a working reactor announced for autumn 2011 in Greece has been canceled; According to sources close to Rossi, a commercial 1 MW reactor that had been announced for years was still only in test operation in September 2015.

After the US company Industrial Heat bought Rossi a license to sell E-Cat-based products, a lawsuit broke out. According to media reports, Rossi demanded outstanding payments of $ 100 million, while Industrial Heat declared the E-Cat non-functional.

Literary and cinematic processing

  • The novel Die Kalte Fusion by Johannes Schmidl plays with the possibility of a successful experiment based on the sonofusion model.
  • In the film Out of Control by Andrew Davis , the sonofusion idea is implemented on film.
  • In the film The Saint , a researcher talks about cold fusion.
  • In his book Ausgebrannt by Andreas Eschbach , a minor character describes cold fusion as the best possible source of energy, which, in her opinion, is rejected by energy companies like Shell in order not to lose the energy monopoly. The procedure is presented as nonsense.
  • The fusion by means of palladium is described in the thriller Die Quelle by Uwe Schomburg.
  • In the British television series Doctor Who, the doctor manipulates Smile on a "Fleishman cold fusion engine"



  • John R. Huizenga: Cold Fusion. The Scientific Fiasco of the Century. Oxford University Press, Oxford 1993, ISBN 0-19-855817-1 .
  • John R. Huizenga: Cold Nuclear Fusion. The miracle that never happened . Vieweg + Teubner, Braunschweig 1994, ISBN 3-528-06614-8 .
  • Frank Close : Too hot to handle - the race for cold fusion. Princeton University Press, Princeton 1991, ISBN 0-691-08591-9 .
  • Frank Close: The hot race for cold fusion. Birkhäuser, Basel 1992, ISBN 3-7643-2631-X .

Journal articles

  • Johann Rafelski , Steven E. Jones : Muon-Catalyzed Cold Nuclear Fusion. In: Spectrum of Science. No. 9, ISSN  0170-2971 , 1987, pp. 124-130.
  • A. Kendl: Ten years later. What was left of the “cold nuclear fusion”? In: Skeptics. 12, ISSN  0936-9244 , 1999, 1-2, p. 32.
  • H. Dittmar-Ilgen: News on sonoluminescence and pyrofusion. In: Naturwissenschaftliche Rundschau. No. 9 ISSN  0028-1050 , 2006, p. 484.

Web links

Individual evidence

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  3. Bart Simon: Undead Science. Science Studies and the After Life of Cold Science A sociological textbook from 2002 about the phenomenon that cold fusion was rejected by the majority of researchers, but a minority continue to research the topic regardless.
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  23. Script for a radio broadcast by Deutschlandfunk from June 5, 2005
  24. 60 Minutes: Once Considered Junk Science, Cold Fusion Gets A Second Look By Researchers , CBS . April 17, 2009. 
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  36. Spontaneous ejection of high-energy particles from ultra-dense deuterium D (0) Accessed September 2015
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