Path: santra!tut!draken!kth!mcvax!uunet!lll-winken!ames!oliveb!pyramid!prls!philabs!linus!munck
From: munck@linus.UUCP (Robert Munck)
Newsgroups: sci.physics
Subject: Polarized D-/D+ storage in Pd as a factor in F&P experiment.
Message-ID: <50901@linus.UUCP>
Date: 20 Apr 89 17:14:10 GMT
Organization: The MITRE Corporation, Bedford MA (just passing it on)
Lines: 107
Return-Path: terry@ctc.contel.com

[A few ideas just for the heck of it:]

HYPOTHESIS -- The critical feature of the F&P reaction is the formation
              of distinct physical regions of D- (palladium deuteride)
              and D+ (mobile deuterons in Pd) under the influence of a
              strong electrical current.  The F&P exothermic reaction
              occurs when conditions permit highly mobile D+ ions to
              recombine or fuse with comparatively immobile D- ions.

FURTHER DESCRIPTION

The D- region would form near the Pd/D20 (anode) interface, while the D+
region would form near the Pd/cathode interface.  There would be no net
electrical polarization of the Pd, since conduction electrons would
redistribute themselves to neutralize charge.  The net result, then, would
be the formation of two physically separated phases of palladium hydride:
a "true" PdD or PdD2 hydride (the D- phase) that would form near the D20
interface, and a highly metallic, deuterons-in-palladium solid solution
(the D+ phase) that would form near the interface to an external cathode.

One nice feature of a polarized D-/D+ phase model is that it jibes well
with the description of an early Fleischmann and Pons experiment, the one
in which a 50% reduction of the input current resulted some time later in
melting (vaporization?) of a palladium cube.  Reducing input current would 
permit mobile D+ ions to diffuse towards the D- phase and react at the
the phase interface.

A "CHEMICAL BATTERY" INTERPRETATION...

If a chemical cause for the F&P release of heat is assumed, then an upper
(and clearly optimistic) limit on energy density can be made by calculating
the energy required to dissassociate a D2 molecule and then ionize it into
D- and D+ ions.  Disassociation of D2 requires 0.218 Mjoule/mole; ionization
of D to D+ is also endothermic and requires 1.312 Mjoule/mole; capture of
an electron by D to form D- is exothermic, producing 0.073 Mjoule/mole.
Each reaction occurs once in D2 --> D- + D+, so the total energy is
1.312 + 0.218 - 0.073 = 1.475 Mjoule/mole of D2.  Obviously, all of this
is no more than an upper limit, since it does not make any attempt to
account for exothermic and/or endothermic reactions of D2 with palladium.

If it is optimistically assumed that all of the D in a 0.6 D:Pd ratio
palladium rod could be ionized and separated, then upper limit for energy
storage would be (0.0343 mole D2 / cm3 Pd) x (1.475 Mjoule/mole D2) -->
50.6 kjoule / cm3 of Pd.  This value is a far cry from the 5 Mjoule per cm3
of Pd that I have seen quoted for the F&P experiment, although it is worth
noting such a system might concentrate its release of energy primarily at
the interface between the D- and D+ phases.

...AND A FUSION INTERPRETATION

If fusion is assumed to be the source of the F&P heat production, then the
chemical reaction of D- and D+ might play a role in bringing about a fusion
reaction at the phase interface.  Of more immediate interest is the fact
that a fusion model based on D-/D+ recombination in Pd would place a number
of strong constraints on how to build such a fusion reactor.  The physical
shape of the Pd would be of particular importance, since those shapes would
need to permit polarization and physical separation of hydride phases.

SOME ASSERTIONS ON HOW TO BUILD AN EFFECTIVE F&P FUSION REACTOR

In particular, a polarized D-/D+ model implies that shapes such as rods and
wires should be highly effective at fusion, while forms such as powdered Pd
would be essentially useless.  It is worth noting that on this point a
D+/D- model makes very different predictions from some of the early
speculation about the importance of surface diffusion, in which it was
suggested that powdered Pd would be dangerously reactive.  Another point
is that Pd rods might be more effective when only one end of the rod
is actually immersed in D20, so as to permit better physical separation
of hydride phases.

If the D-/D+ model is valid, the most effective (and dangerous) form of the
F&P experiment would be to use a palladium sphere in which a hole has been
drilled to the center, and an insulated (except for the end) cathode wire
inserted into the hole.  (Intimate electrical contact at the center, such
as through the use of a molten solder prior to inserting the wire, would
be helpful.)  The junction of the wire with the surface of the sphere should
be made watertight ("heavywatertight?"), and the entire sphere placed in
heavy water.  This design would "trap" the mobile D+ phase within a
surrounding shell of the D- phase, while simultaneously providing a fairly
large Pd/D20 surface area for diffusion of deuterium into the palladium.

APPROACHES TO VERIFYING D-/D+ PALLADIUM HYDRIDE PHASES

If physically separated hydride phases can exist in Pd, they should be
readily detectable by their effects on the properties of the Pd.  The D-
phase would presumably be less metallic and more like conventional "true"
(vs. interstitial) transition element hydrides, while the D+ phase should
remain highly conductive and generally more metallic in properties.

If they exist, the stability of physically separted D+ and D- phases over
time would be interesting to investigate.  If both are comparatively stable
(which I rather doubt), they could be physically separated and later allowed
to react by placing them placed in contact with each other.  Current reversal
(anode to P+ phase, cathode to D- phase) might also be an interesting (and
probably dangerous) approach to increasing the reaction rate at the P-/P+
phase interface.

If they exist in palladium, P- and P+ phases could very well exist in other
transition elements, since a number of such elements have been shown to
carry current via H+ ions.  Two good candidates from this line of reasoning
are titanium (sound familiar?) and, less obviously, tantalum.

				Cheers,
				Terry Bollinger  (terry@ctc.contel.com)

				"Life's too short to be in
				 a hurry all of the time."