STM-D-0911Paper2005Published and peer-reviewed

Laser Stimulation of Deuterated Palladium: Past and Present

Dennis Letts · Dennis Cravens

Summary and citation · read the original at the source · none found

In one page

Dennis Letts works out of a home laboratory in Austin, Texas; Dennis Cravens is a physicist in New Mexico. This is the paper in which they told a conference how to make the effect happen on demand. Their recipe has two halves. First the metal: a seventeen-step protocol of polishing, etching, cold rolling and annealing that grows the grains of a palladium strip before any deuterium goes in, followed by days of loading in a small magnetic field and then a coat of gold plated on from solution. Then the trigger: an ordinary red laser diode, thirty milliwatts, aimed at a two-millimetre spot on that cathode. The cell warms by five to thirty times what the laser light alone could deliver — typically half a watt, once close to a full watt. Turn the laser off and the heat decays. Rotate the beam’s polarization against the magnet and the heat rises and falls with it. Letts and Cravens argue the value of the method is control.

Why it matters hereChapter 12 needs an experiment with a switch on it, and this is where that switch was first described in public: metallurgy that makes cathodes respond consistently, and a laser that starts and stops the heat within minutes. Everything later in the Letts line — the two-laser beat frequencies, Hagelstein’s phonon models — is built on the protocol set out here.

What it claims

01A method is disclosed to fabricate a palladium cathode that can be electrolysed in heavy water and stimulated with a laser at a predetermined wavelength to produce apparent excess power. The fabrication involves cold working, polishing, etching and annealing the palladium before electrolytic loading with deuterium; loading is done with the cathode sitting in a magnetic field of 350 gauss; gold is then co-deposited electrolytically onto the cathode; and the cathode is stimulated with a low-power laser of at most 30 milliwatts. The thermal response is typically 500 milliwatts, with a maximum observed of approximately 1 watt.Abstract; section 4, Cathode Fabrication, the seventeen-step protocol
Published and peer-reviewed
02A common red laser of 30 milliwatts, tuned to specific wavelengths, triggers a cathodic exothermic reaction five to thirty times greater than the magnitude of its radiant power output, and the effect has not disappeared or diminished as calorimetric quality improved. In one run a 682.3 nanometre laser switched on at minute 30 drove the cell to a maximum excess power of 350 milliwatts, and the signal declined to baseline when the laser was switched off at minute 134. The irradiated area was about 0.03 square centimetres, giving a surface power density of 10 watts per square centimetre against the 1 watt per square centimetre of the best solid-oxide fuel cells of the day.Section 5, Results, and Figure 6, run DGL560a10
Published and peer-reviewed
03The size of the response tracks the surface treatment, not just the laser. Two runs on 11 and 12 October 2002 used the same 661.5 nanometre laser at the same 30 milliwatts; the principal difference was the amount of gold plated onto the cathode, and the cathode that had received a further 24 hours of gold co-deposition gave a thermal response three times greater. The excess heat also depends on where on the cathode the laser spot falls, which lets a single cathode be surveyed spot by spot.Section 5, Results, Figures 7 and 8, runs DGL578c and DGL578g; section 9, Discussion
Published and peer-reviewed
04The heat responds to the polarization of the light relative to an external magnetic field. Cravens noticed that the response is maximised when the beam polarization is perpendicular to the 350 gauss field. Rotating the polarization parallel to the field with a half-wave retarder weakened the signal immediately; removing the retarder recovered it; re-inserting it drove the signal back down to about the level of plain laser heating. The retarder itself attenuates the 30 milliwatt beam by roughly 1 milliwatt, and the authors observe that it is hard to conceive of any error that leads to variation in excess heat as the beam polarization is changed.Section 6, Polarization, Figures 9 and 10, run DGL565b24
Published and peer-reviewed
05The effect has been produced outside the authors’ own laboratory and in front of witnesses. Experiment 587e was run at the laboratories of EarthTech International in Austin and witnessed by Scott Little, George Miley, Edmund Storms and Tom Claytor: a palladium-on-gold cathode with a rare-earth additive from Cravens became responsive at 657 nanometres and 30 milliwatts, excess power rose to 500 milliwatts over fifteen hours with ambient held to 24 degrees Celsius plus or minus five hundredths and cell power to 7 watts plus or minus a hundredth, and the recovery from 250 to 750 milliwatts after the laser was switched back on was witnessed by all four. A cell was also run as a live internet demonstration during the ICCF-10 presentation on 26 August 2003, giving about 500 milliwatts of excess against 500 milliwatts of direct-current cell power.Section 5, Results, Figure 11, experiment 587e; section 7, Conference Demonstration Cell 602
On the bench now
06What to watch: the wavelength rule, and why it works. Letts offers a particle-in-a-box model in which deuterium sits in a quantum well between palladium surface atoms, of width 0.954 angstroms — the beta-phase lattice parameter of 4.026 angstroms less twice the palladium-deuterium equilibrium distance — giving resonant wavelengths of 679.91 and 684.83 nanometres for two particular sets of quantum numbers. The authors are explicit that the model’s only redeeming quality is that it provides a method to tune the laser, and that there is no physical reason why the wavelengths should work other than luck. What matters, they say, is the experimental fact that the effect depends on frequency, and the tests that follow from it: sources nearer the more populated ground states, and the one red diode in the standard range, 635 nanometres, they had not yet tried.Section 8, Crude Model, equations 1 to 4; section 9, Discussion
What to watch

The way in

https://doi.org/10.1142/9789812701510_0015SOURCE REACHED AND READ IN FULL. Presented at the Tenth International Conference on Cold Fusion, Royal Sonesta Hotel, Cambridge, Massachusetts, August 2003, and published as pages 159 to 170 of Condensed Matter Nuclear Science: Proceedings of ICCF-10, World Scientific, dated December 2005. The published volume is closed and Unpaywall and OpenAlex report no open deposit on 2026-09-08. The authors’ own conference version is posted in full by LENR-CANR at lenr-canr.org/acrobat/LettsDlaserstimu.pdf, and that ten-page copy was downloaded and read for this sheet on 2026-09-08; its first page states that it was the paper presented at the conference and that it may differ from the version published by World Scientific. It carries no Creative Commons statement, so no text of it is reproduced here. The summary, the claims and every locator come from that reading and use the paper’s own numbered sections and figure numbers. The title and the authors’ names are printed in full capitals by the publisher and are given here in normal case. Addresses as printed: Dennis Letts, Austin, Texas; Dennis Cravens, Cloudcroft, New Mexico.

How to cite it

Dennis Letts, Dennis Cravens (2005) Laser Stimulation of Deuterated Palladium: Past and Present. doi:10.1142/9789812701510_0015

Where it sits in the curriculum

Lattice confinement fusion