557 lines
22 KiB
Plaintext
557 lines
22 KiB
Plaintext
typing and I formatted it in ASCII. Much thanks to Mike Attas for additional
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corrections.
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WARNING: This text will contain errors. Consider it a poor facsimile of the
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original paper since that's what is was transcribed from. Be especially wary
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of numbers and symbols since these are the hardest to decipher from context.
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Question marks in the text indicate severe ambiguity.
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If anyone has a better copy, please post corrections or send them to
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pphillip@cs.ubc.ca.
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--------
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Electrochemically Induced Nuclear Fusion of Deuterium
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Martin Fleischmann
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Department of Chemistry
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The University
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Southhampton, Hants. S09 5NH
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ENGLAND
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Stanley Pons*
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Department of Chemistry
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University of Utah
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Salt Lake city, UT 84112 USA
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Submitted to Journal of Electroanalytical Chemistry March 11,
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1989; in final form March 20, 1989
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* To whom correspondence should be addressed.
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INTRODUCTION
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The strange behavior of electrogenerated hydrogen dissolved in
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palladium has been studied for well over 100 years and, latterly
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these studies have been extended to deuterium and tritium [1].
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For discharge of deuterium from alkaline solutions of heavy water
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we have to consider the reaction steps:
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- -
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D O + e -> D + OD (i)
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2 ads
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- -
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D + D O + e -> D + OD (ii)
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ads 2 2
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D -> D (iii)
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ads lattice
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D + D -> D (iv)
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ads ads 2
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It is known that at potentials negative to +50 mV on the
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reversible hydrogen scale the lattice is in the beta-phase,
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hydrogen is in the form of protons (as shown by the migration in
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an electric field) and is highly mobile (D = 10E-7 cm*cm/s for
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the alpha-phase at 300K).
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The overall reaction path of D2 evolution consists of steps (i)
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and (ii) [2] so that the chemical potential of dissolved D+ is
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normally determined by the relative rates of these two steps.
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The establishment of negative overpotentials on the outgoing
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interface of palladium membrane electrodes for hydrogen discharge
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at the ingoing interface [3] (determined by the balance of all the
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steps i) to (iv)) demonstrates that the chemical potential can be
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raised to high values. Our own experiments with palladium
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diffusion tubes indicate that values as high as 0.8 eV can
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readily be achieved [4] (values as high as 2eV may be achievable).
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The astronomical magnitude of this value can readily be
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appreciated; attempts to attain this level via the compression of
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D2 (step (iv)) would require pressures in excess of 10E24
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atmospheres. In spite of this high compression, D2 is not
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formed; i.e. the s-character of the electron density around the
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nuclei is very low and the electrons form part of the band
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structure of the overall system. A feature which is of special
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interest and which prompted the present investigation is the very
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high H/D separation factor for absorbed hydrogen and deuterium
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(see Figs. 4 and 6 of Ref [2]). This can only be explained if
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the H+ and D+ in the lattice behave as classical oscillators
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(possibly as delocalised species) i.e. they must be in very
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shallow potential wells. In view of the very high compression
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and mobility of the dissolved species there must therefore be a
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significant number of close collisions and one can pose the
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question: would nuclear fusion of D+ such as
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2 2 3 1
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D + D -> T(1.01 MeV) + H(3.02 MeV) (v)
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or
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2 2 3
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D + D -> He(0.82 MeV) + n(2.45 MeV) (vi)
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be feasible under these conditions?
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EXPERIMENTAL
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In the work reported here D+ was compressed galvanostatically
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into sheet, rod and cube samples of Pd from 0.1 M LiOD in 99.5%
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D2O + 0.5% H2O solutions. Electrode potentials were measured
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with respect to a Pd-D reference electrode charged to the alpha-
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beta-phase equilibrium. We report here experiments of several
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kinds:
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1) Calorimetric measurements of heat balances at low current
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densities (=1.6 mA/cm*cm) were made using a 2mm x 8cm x 8cm Pd
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sheet cathode surrounded by a large Pt sheet counter electrode.
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Measurements were carried out in Dewar cells maintained in a
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large constant temperature water bath (300K), the temperature
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inside the cell and of the water bath being monitored with
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Beckman thermometers. The Heavy Water Equivalent of the Dewar
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and contents and the rate of Newton's law of cooling losses were
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determined by addition of hot D2O and by following the cooling
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curves.
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2) Calorimetric measurements at higher current densities
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were carried out using 1, 2 and 4mm diameter x 10 cm long Pd rods
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surrounded by a Pt wire anode wound on a cage of glass rods. The
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Dewars were fitted with resistance heaters for the determination
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of Newton's law of cooling losses; temperatures were measured
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using calibrated thermistors. Experiments with rods up to 2 cm
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in diameter will be reported elsewhere [5]. Stirring in these
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experiments (and in those listed under 1)) was achieved, where
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necessary, by gas sparging using electrolytically generated D2.
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Measurements at the highest current density reported here
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(512 mA/cm*cm) were carried out using rods of 1.25 cm length; the
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results given in Table 1 have been rescaled to those for rods of
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10 cm length.
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3) The spectrum of gamma-rays emitted from the water bath due to
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the (n,gamma) reaction
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1 2
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H + n(2.45 MeV) -> D + gamma(2.5 MeV) (vii)
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was determined using a sodium iodide crystal scintillation
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detector and a Nuclear Data ND-6 High Energy Spectrum analyzer.
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The spectrum was taken above the water immediately surrounding an
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0.8 x 10 cm Pd-rod cathode charged to equilibrium; it was
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corrected for background by subtracting the spectrum over a sink
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(containing identical shielding materials) 10 m from the water
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bath.
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The neutron flux from a cell containing a 0.4 x 10 cm Pd-rod
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electrode was measured using an Harwell Neutron Dose Equivalent
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Rate Monitor, Type 95/0945-5. The counting efficiency of this
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Bonner-sphere type instrument for 2.5 MeV neutrons was estimated
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to be 2.4 x 10E-4 and was further reduced by a factor of 100 due
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to the unfavorable configuration (the rod opposite the BF filled
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3
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detector). The background count was determined by making
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measurements 50m from the laboratory containing the experiments;
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both locations were in the basement of a new building which is
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overlain by 5 floors of concrete. In view of the low counting
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efficiency, counting was carried out for 50 hours. Measurements
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on a 0.4 x 10 cm rod electrode run at 64 mA/(cm*cm) gave a
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neutron count 3 times above that of the background.
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4) The rate of generation/accumulation of tritium was
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measured using similar cells (test tubes sealed with Parafilm)
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containing 1 mm diameter x 10 cm Pd rod electrodes. Measurements
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on the D/T separation factor alone were made using an identical
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cell containing a 1 mm diameter x 10 cm Pt electrode (this
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measurement served as a blank as the H/D separation factors on Pd
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and Pt are known to be closely similar). 1 ml samples of the
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electrolyte were withdrawn at 2 day intervals, neutralised with
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potassium hydrogen phthalate and the T-content was determined
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using Ready Gel liquid scintillation "cocktail" and a Beckman LS
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5000 TD counting system. The counting efficiency was determined
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to be about 45% using standard samples of T-containing solutions.
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The beta-decay scintillation spectrum was determined using the
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counting system.
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In these experiments standard additions of 1 ml of the electrolyte
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were made following sampling. Losses of D2O due to electrolysis
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in these and all the other experiments recorded here were made up
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using D2O alone. A record of the volume of D2O additions was
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made for all the experiments.
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In all of the experiments reported here all connections were
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fitted into Kel-F caps and the caps were sealed to the glass
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cells using Parafilm.
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Results for the mass spectroscopy of the evolved gases and full
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experimental details for all the measurements will be given
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elsewhere [5].
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RESULTS
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1) and 2)
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In the calorimetric experiments we can set lower and upper bounds
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on the rates of Joule heating depending on whether reactions (i),
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(ii) , and (iv) are balanced by
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- -
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4OD -> D O + O + 4e (viii)
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2 2
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at the anode or by the reverse of reactions (i), (ii), and (iv).
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In the former case the Joule heating is simply the cell current
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multiplied by (cell voltage - 1.54 V) where 1.54 V is the cell
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voltage at which reactions (i), (ii), and (iv) balanced by (viii)
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are thermoneutral: irreversibilities in the electrode reactions
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and ohmic resistance losses have identical effects on the Joule
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heating. However, if reactions (i), (ii), and (iv) are reversed
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at the anode and, equally, if the reverse of reactions (viii)
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contributes to the cathode processes, then we get an upper bound
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to the Joule heating which is simply the cell current multiplied
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by the cell voltage.
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We have confirmed in long duration experiments that the rates of
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addition of D2O to the cells required to maintain constant
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volumes are those for reactions (i), (ii), and (iv) balanced by
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reaction (viii). Furthermore, subtraction of the ohmic potential
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losses in solution for the cell containing the large Pt-anode
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shows that the electrolysis of D2O is the dominant process, i.e.
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we have to assume that the Joule heating is close to the lower
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bound.
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Table 1 gives the results for experiments designed to cover the
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effects of electrolyte geometry, electrode size, current density
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(or overpotential) method of operation, etc. The nature and
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large magnitude of the effects can be appreciated from the
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following observations:
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a) excess enthalpy generation is markedly dependent on the
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applied current density (i.e. magnitude of the shift in the
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chemical potential) and is proportional to the volume of the
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electrodes; i.e. we are dealing with a phenomenon in the bulk of
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the Pd-electrodes.
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b) enthalpy generation can exceed 10 watts/(cm*cm*cm) of the
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palladium electrode; this is maintained for experimental times in
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excess of 120 hours during which typically heat in excess of
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4MJ/(cm*cm*cm) of electrode volume was liberated. It is
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inconceivable that this could be due to anything but nuclear
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processes.
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c) in research on thermonuclear fusion, the effects are
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expressed as a percentage of the breakeven where 100% breakeven
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implies that the thermal output equals the input (neglecting the
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power required to drive the equipment). In electrochemical
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experiments we have additionally to take into account whether
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breakeven should be based on the Joule heat or total energy
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supplied to the cell. Furthermore, in the latter case the energy
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supplied depends on the nature of the anode reaction. Table 2
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lists three such figures of merit and it can be seen that we can
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already make reasonable projections to 1000%. Some of the
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factors important to scale-up are already apparent from Tables 1
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and 2.
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d) the effects have been determined using D2O alone.
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Projections to the use of appropriate D2O/DTO/T2O mixtures (as is
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commonly done in fusion research) might therefore be expected to
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yield thermal excesses in the range 10E3 - 10E4 % (even in the
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absence of spin polarisation) with enthalpy releases in excess of
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10 kW/(cm*cm*cm). We have to report here that under the
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conditions of the last experiment even using D2O alone, a
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substantial portion of the cathode fused (melting point 1554
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degrees C) part of it vapourised and the cell and contents and a
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part of the fume cupboard housing the experiment were destroyed.
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TABLE 1. Generation of excess enthalpy in Pd-cathodes as a
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function of current density and electrode size.
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Cube Sheet Rod Rod Rod electrode type
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1x1x1 cm 0.2x8x8cm 0.4x10cm 0.2x10cm 0.1x10cm dimensions
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125 0.8 8 8 8 current density (mA/cm*cm)
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WARNING 0.153 .153 .036 .0075 excess rate of heating
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(watts/cm*cm*cm)
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IGNITION?
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(see text) 0 .122 .115 .095 excess specific rate of
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heating (watts/cm*cm*cm)
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250 1.2 64 64 64 current density (mA/cm*cm)
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.027 1.751 .493 .079 excess rate of heating
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(watt)
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.0021 1.39 1.57 1.01 excess specific rate of
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heating (watts/cm*cm*cm)
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1.6 512 512 512 current density *
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(mA/cm*cm) *
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0.79 26.8 3.02 .654 excess rate of heading
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(watt) *
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.0061 21.4 9.61 8.33 excess specific rate of
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heating (watts/cm*cm*cm)
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* Measured on electrodes of length 1.25 cm and rescaled to 10 cm.
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TABLE 2. Generation of excess enthalpy in Pd rod cathodes
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expressed as a percentage of breakeven values.
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0.4x10cm 0.2x10cm 0.1x10cm dimensions
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8 8 8 current density (mA/cm*cm)
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111 62 23 excess heating * (% of breakeven) *
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53 27 12 excess heating** (% of breakeven) **
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1224 286 60 excess heating*** (% of breakeven) ***
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64 64 64 current density (mA/cm*cm)
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66 46 19 excess heating * (% of breakeven) *
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45 29 11 excess heating** (% of breakeven) **
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438 247 79 excess heating*** (% of breakeven) ***
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512 512 512 current density (mA/cm*cm)
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59 14 5 excess heating * (% of breakeven) *
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48 11 5 excess heating** (% of breakeven) **
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839 189 81 excess heating*** (% of breakeven) ***
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* % of breakeven based on Joule heat supplied to
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cell and anode reaction
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- -
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4OD -> 2D O + O + 4e
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2 2
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** % of breakeven based on total energy supplied to
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cell and anode reaction
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- -
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4OD -> 2D O + O + 4e
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2 2
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*** % of breakeven based on total energy supplied to
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cell and for an electrode reaction
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- -
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D + 2OD -> 2D O + 4e
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2 2
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with a cell potential of 0.5V.
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2 2
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All %'s based on D + D reactions, i.e. no projection
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to [next line lost in scanning]
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3) Fig. 1A illustrates the gamma-ray spectra which have been
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recorded in regions above the water bath adjacent to the
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electrolytic cells and this spectrum confirms that 2.45 MeV
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neutrons are indeed generated in the electrodes by reaction (vi).
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These gamma-rays are generated by the reaction (vii). We note
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that the intensities of the spectra are weak and, in agreement
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with this, the neutron flux calculated from the measurements with
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the dosimeter is of the order 4 x 10E4 1/s for a 0.4 x 10 cm rod
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electrode polarised at 64 mA/(cm*cm).
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Figure 1A
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gamma-ray spectrum recorded above the water bath containing the
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rod cathodes. Measurements carried out with a sodium iodide
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crystal scintillation detector and a Nuclear Data ND-6 High
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Energy Spectrum Analyzer. The background in this region (taken
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over a water bath 5 m from the experiment containing identical
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shielding materials) is level at about 400 counts; spectrum
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accumulation time: 48 hours.
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4) In agreement with this low neutron flux, the accumulation
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in the electrolyte also indicates a low rate for reaction (v)
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(which has been found to be somewhat faster than (vi) in high
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energy physics experiments). The time dependent fraction of
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tritium in the solvent can be shown to follow(?)
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(1):
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-(1 + lambda * delta )*Rt
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D,T
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alpha = gamma * exp ---------------------------
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T T lambda * S * N
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D,T
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delta
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D,T
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+ ((1 + lambda)gamma + beta/R) * --------------------- * -+
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T (1 + lambda*delta ) |
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D,T |
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+-------------------------------------------+
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| -(1 + lambda * delta )Rt
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| D,T
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+--> * (1 - exp --------------------------)
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lambda*S * N
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D,T
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where:
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gamma is the fraction of T in the electrolyte/solvent feeds,
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T
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lambda * R (atoms T/s, here 4x10E11 atoms/s) is the sampling rate
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which has been assumed to be continuous in time,
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N is the total number of atoms of D in the Dewar (14.6x10E23),
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S is the D/T separation factor,
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D,T
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beta is the rate of the nuclear reaction (v) (events/s), and
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R is the rate of electrolysis expressed as atoms D 1/s
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(here 1.24x10E14(?) atoms/s)
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It can be seen that the final value alpha for the cell containing
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T
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the Pt-cathode (for which we assume beta = 0) is:
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A
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delta
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D,T
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alpha = ((1 + lambda)*gamma + beta/R) * ---------------------- (1)
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T T (1 + lambda * delta )
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D,T
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Blank experiments using Pt-cathodes (which have very similar
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separation factors to Pd) indicate little accumulation of DTO so
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that S is close to unity under the conditions of our
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D,T
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experiments. DTO accumulates in the cells containing Pd cathodes
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to the extent of about 100dpm/ml of electrolyte and Fig. 1B
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demonstrates that the species accumulated is indeed tritium. Use
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of equation (2) then indicates that reaction (v) takes place to
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the extent of 1-2 x 10E4 atoms/s which is consistent with the
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measurements of the neutron flux, bearing in mind the difference
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in radii. On the other hand the data on enthalpy generation
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would require rates for reactions (v) and (vi) in the range 10E11-
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10E14 atoms/s. It is evident that reactions (v) and (vi) are
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only a small part of the overall reaction scheme and that other
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nuclear processes must be involved.
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(see figure on trailing pages)
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Figure 1B
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beta-ray disintegration scintillation spectrum measured with a
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Bockman LS5000TD counter-spectrometer.
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DISCUSSION
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We realise that the results reported here raise more questions
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than they provide answers and that much further work is required
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on this topic. The observation of the generation of neutrons and
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of tritium from electrochemically compressed D+ in Pd cathode is
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in itself a very surprising result and, evidently, it is
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necessary to reconsider the quantum mechanics of electrons and
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deuterons in such host lattices. In particular we must ask: is
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it possible to achieve a fusion rate of 10E-19 1/s for reactions
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(v) and (vi) for clusters of deuterons (presumably located in the
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octahedral lattice positions) at typical energies of 1eV?
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Experiments on isotopically substituted hydrides of well defined
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structures might well answer this question.
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The most surprising feature of our results however, is that
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reactions (v) and (vi) are only a small part of the overall
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reaction scheme and that the bulk of the energy release is due to
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an hitherto unknown nuclear process or processes (presumably
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again due to clusters of deuterons). We draw attention again to
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the very large magnitude of the effects in the confinement
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parameter diagram, fig. 2. We note that the values of the
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confinement parameter are extremely high compared to conventional
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research on fusion (high particle densities, lifetimes of 10E2 -
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10E4 years) while the chemical potential is very low compared to
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the equivalent parameter, (T), in those experiments. It is
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evident that diagrams of this kind require extension in the third
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dimension for electrochemical experiments since the results are
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so markedly dependent on electrode volume (increase of current
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density displaces the points in a vertical direction). We draw
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attention again to the fact that the experiments already carried
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out are close to the breakeven point; further work to extend the
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electrode dimension (and to establish the nature of the processes
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responsible for the enthalpy release) is in progress. Finally, we
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urge the use of extreme caution in such experiments: a plausible
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interpretation of the experiment using the Pd-cube electrode is
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in terms of ignition. Projection of the values in Tables 1 and 2
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to more extreme conditions indicate that this may indeed be
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feasible.
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Figure 2
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2 2
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Confinement parameter-chemical potential-size diagram for D + D
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2 3
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fusion reaction in Pd-cathodes, projection to the D + T
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reaction.
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ACKNOWLEDGEMENT
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We wish to thank Johnson Matthey PLC for the loan of precious
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metals for this project.
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LITERATURE REFERENCES
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1. W. M. Mueller, J. T. Blacklodge, G. G. Libowitz, "Metal
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Hydrides", Academic Press, New York (1968); G. Bambakadis, Ed.,
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"Metal Hydrides", Plenum Press (1981).
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2. B. Dandapani and M. Fleischmann, Journal of Electroanalytical
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Chemistry, 12 (1972) 323.2.39
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3. A. N. Frumkin and N. A. Aladzhalova, Acta Physicochim.
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|
U.R.S.S., 2 (1940) 1.9
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4. Unpublished results
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5. M. Fleischmann, M. Hawkins, and B. Pons, to be published.
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