HEAT AND HELIUM

2 X 10 ), therefore the mantle also has a diagnostic He/heat ratio that can be estimated from measurements of the He and Heat fluxes in oceanic basins. This can be used to tease apart fractionation of He and heat during transport across the mantle-crust boundary and fractionation of He and Heat that were produced in the crust. 

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Figure 5.2 A, valve, column and flow cell asseidily of a ainiaturized liquid chromatograph for use with small bore columns (Reproduced with permission from ref. 14) and B, mobile phase reservoir designed for solvent degassing by heat and helium sparging (Reproduced with permission from ref. 34. Copyright Elsevier Scientific Publishing Co.)...

Farley K. A., Love S. G., and Patterson D. B. (1997) Atmospheric entry heating and helium retentivity of interplanetary dust particles. Geochim. Cosmochim. Acta... 

O Nions RK, McKenzie D (1993) Estimates of mantle thorium/uranium ratios from Th, U and Pb isotopic abnndances in basaltic melts. Phil Trans R Soc Lond A342 65-74 O Nions RK, Oxbnrgh ER (1983) Heat and helium in the Earth. Nature 306 429-431 O Nions RK, Tolstikhin IN (1994) Behaviour and residence times of lithophile and rare gas tracers in the npper mantle. EarthPlanet Sci Lett 124 131-138... 

Heat and helium. The present and past thermal state of the mantle provides lines of evidence that support some form of convective isolation (van Keken et al. 2001, 2002). 

Figure 7. Numerical models can be used to assess the variance in natural heat and helium fluxes without assuming steady state conditions, as well as to consider the effect of secular cooling on the convection rate. In similar models to those used to investigate the mixing and degassing of me and " He (van Keken and Ballentine 1998, van Keken and Ballentine 1999 see Fig. 8). van Keken, Ballentine et al. (2001) show that a model of whole mantle convection produces a large variance in the " He flux at mid ocean ridge analogues (a), but with much smaller variance in the heat flux extracted across the entire model surface (b). The variance in the combined ""He/heat ratio is dominated by the variance in the He flux, and matches the very low present day " He/heat ratio ( He...

TW of mantle heat must cross from the layer into the convecting mantle, neglecting any component of secular cooling (see Heat and helium section). It is not yet clear what this effect would have on the thermal stability of the layer or temperature contrast with the overlying mantle. 

Transport of mantle heat and helium through the crust... 

Fleischmann and Pons were actually the first to observe the production of helium-4 in the Pd/D system [4]. However, due to the extensive criticism of their 1989 announcement, they did not want ... to open another front for attacks on their work, and so their measurements of helium-4 were never officially reported. The first reported experiments correlating the calorimetric excess enthalpy and helium-4 production were conducted by Miles in 1990 at the Naval Weapons Center (now NAWCWD) in China Lake, California, and the helium measurements were performed under the supervision of Bush at the University of Texas [6-8]. The presence of helium-4 was observed in eight out of nine effluent gas samples collected during the presence of excess heat [7,8]. No helium-4 was observed for six out of the six samples of effluent gas for a Pd/H20 control study. Measurements were also conducted for heUum-3 in these studies, but none was detected [6]. In summary, for all experiments conducted by Miles at NAWCWD, 12 out of 12 produced no excess helium-4 when no excess heat was measured, and 18 out of 21 experiments gave a correlation between the measurements of excess heat and helium-4 [8, 18]. Three of the experiments that produced hehum-4 were conducted under double-blind rules [8, 18]. An exact statistical treatment for all experiments shows that the probability is only one in 750 000 that the China Lake set of heat and helium-4 measurements could be this well correlated due to random experimental errors [18]. Furthermore, the rate of helium-4 production was always in the appropriate range of 10 to 10 atoms per second per watt of excess power for D -I- D or other likely nuclear reactions [8,18]. 

An early confirmation for the correlation of excess heat and helium production in the Pd/D system was reported by McKubre and coworkers at SRI [9]. Several different experiments, using three different calorimetric methods, gave a strong time correlation between the rates of heat and helium production [9]. The production of helium-4 was also observed in sealed cells containing a Pd-C catalyst and D2 gas where the helium increase exceeded the amount of helium-4 in room air [39]. There are a number of other reports of helium4 production in Pd/D systems [3], including those of Gozzi in Italy [40], DeNinno in Italy [40], and Arata in Japan [41]. 

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