Historical research guide · 0511 · 2012
Cryogenic Calorimetry of “Exploding” PdDx Wires
F. L. Tanzella · J. Bao · M. C. H. McKubre
In one minute
Francis Tanzella, Jianer Bao and Michael McKubre of SRI International needed a way to measure a burst of heat too small and too fast for an ordinary calorimeter, so they built one out of liquid nitrogen. A hair-thin palladium wire sits in a nitrogen bath at 77 kelvin, a current pulse runs through it, the nitrogen it heats boils off, and a flow meter integrates the puff of gas. The instrument resolves less than a tenth of a joule at an accuracy near 0.06 joule, and nine blank palladium wires came out on the theoretical line. The wires that matter are loaded first: high-voltage electrolysis of very pure heavy water drives deuterium into the palladium until there is close to one deuterium atom per palladium atom, and a mercury amalgam seals the surface so it cannot leak back out. Pulsed hard at 77 kelvin, those loaded wires disintegrate into fine powder, and five of the seven released more energy than was put in, by roughly eighteen to fifty-two per cent.
Connection
Chapter 12 asks whether a metal lattice packed with deuterium does nuclear-scale work at ordinary temperatures, and this paper answers with an instrument rather than an argument: a calorimeter calibrated against a resistor and against nine blank wires before a single loaded wire is fired. That control discipline is what chapter 1’s evidence ladder is built to reward — the excess energy is claimed only where it stands clear of a stated error bar, and the authors name the measurement that would settle the mechanism.
From the source
A cryogenic calorimeter operating at 77 kelvin, which reads the volume of nitrogen boiled off by a sub-tenth-of-a-second current pulse, achieves a minimum detectability of less than 0.1 joule and an accuracy of less than 0.06 joule, calibrated across roughly 0.2 to 5 joules against a 10 ohm resistor.Abstract; Section 2.2; Section 3.1 with Figure 4
Nine blank palladium wires stimulated in the same calorimeter gave measured gas volumes within plus or minus 0.25 millilitre of the theoretical value, confirming that no excess heat is generated with unloaded wires and that the calorimeter yields repeatable results.Section 3.1 with Figure 5
The Celani and Tripodi technique of loading thin palladium wires to a deuterium-to-palladium ratio near unity and sealing the surface with a mercury amalgam, tracked in situ by the four-wire resistance ratio, extends from light water to heavy water and the loaded wires survive transfer into the calorimeter without loss of loading.Section 2.1; Section 3.2 with Figures 6 and 7; Section 4
Of seven deuterium-loaded wires, five released energy clearly above the stated error range, from 18.4 per cent plus or minus 8 to 51.9 per cent plus or minus 7 more than the input, with output energies as high as 150 per cent of input; the amount is generally much larger than anything measured from the hydrogen-loaded wires.Section 3.3, Table 1 and Figure 9; Section 4 Conclusions
Highly loaded PdDx wires disintegrate into microscopic particles when high current density pulses are passed through them at 77 kelvin, and in every case observed so far that disintegration is accompanied by excess energy; whether a wire disintegrates or simply breaks appears to be set by defects in the wire itself rather than by its loading.Abstract, final two sentences; Section 3.3; Section 4 Conclusions
No correlation can yet be made between average deuterium loading level and excess energy; the next measurements named are helium isotope analysis of the gas collected from the calorimeter headspace during the pulses, vaporization-inlet mass spectrometry of the palladium fragments, and more hydrogen-loaded wires run on a stable baseline for a statistically significant comparison.Section 4, Conclusions and Future Work
The way in
https://doi.org/10.70923/001c.72164How to cite it
F. L. Tanzella, J. Bao, M. C. H. McKubre (2012) Cryogenic Calorimetry of “Exploding” PdDx Wires doi:10.70923/001c.72164