The use of the compressional hydromagnetic mode (also called the magnetosonic or, simply, the fast wave) is examined in some detail with respect to the heating of a tritium plasma containing a few percent deuterium. Efficient absorption of wave energy by the deuteron component is found when ω = ωC (deuterons), with Qwave 100. Reasonable efficiencies are found also for electron heating, but coherence effects between transit-time and Landau damping for electrons reduce the total absorption for both processes to one-half of the transit-time power, calculated separately.The fusion output of a two-component neutral-injected plasma can be enhanced by selective heating of the injected deuterons. Also, selective deuteron absorption may be used for ion-tail creation by radiofrequency excitation alone, as an alternative to neutral injection. The dominant behaviour of the high-energy deuteron distribution function is found to be f(v) ~ exp[(3/2)∫vdv / ], where is the Chandrasekhar-Spitzer drag coefficient, and is the Kennel-Engelmann quasi-linear diffusion coefficient for wave-particle interaction at the deuteron cyclotron frequency. An analytic solution to the one-dimensional Fokker-Planck equation, with r.f.-induced diffusion, is developed, and using this solution together with Duane's fit to the D-T fusion cross-section, it is found that the nuclear-fusion power output from an r.f.-produced two-component plasma can significantly exceed the incremental (radiofrequency) power input.

Fast-wave heating of a two-component plasma

The paper summarizes the basic information on the equilibrium of a toroidal plasma column in systems of the Tokamak type. It considers the methods of maintaining a plasma in equilibrium with the help of a conducting casing, an external maintaining field and the iron core of a transformer. Attention is paid to the role of the inhomogeneity of the maintaining field. It is shown in particular how the shape of the column cross-section depends on the curvature of the lines of force of the maintaining field. For the case (which has practical importance) weak asymmetry of the field distribution in the transverse cross-section, this paper describes a uniform method of consideration, which takes into account the influence of different factors on the equilibrium position of the column. This method is used for calculating plasma equilibrium in a Tokamak model with a conducting casing. Account is here taken of the effect of gaps in the casing and of finite electrical conductivity. Some cases of plasma equilibrium which are outside the standard Tokamak scheme are also considered, such as equilibrium in a conducting shell having the shape of a racetrack, equilibrium where the whole current is transferred by relativistic runaway electrons and equilibrium at high plasma pressure βI ~R/a.

https://iopscience.iop.org/article/10.1088/0029-5515/11/6/005/pdf

Plasma equilibrium in a Tokamak

Publisher Summary This chapter overviews the Patagonian and Fuegian glaciations—starting in the Late Miocene, when the junction of global, cooler climatic conditions, and the final rise of the southern Andes enabled the formation of mountain glaciers in the area. The chapter presents the absolute chronology of the Patagonian terrestrial glacial sequences, basically dated by means of 40 Ar/ 39 Ar dating techniques on volcanic rocks associated with glacial landforms and deposits, and cosmogenic isotope dating techniques on erratic boulders and glacial erosional surfaces. In some cases, the magnetostratigraphy of glacial deposits is available, thus allowing the correlation with the Pampean continental sequences and with the global ocean record. Patagonia and Tierra del Fuego are some of the regions of the world still largely covered by ice and snow. Three major mountain ice sheets can be observed along the Patagonian and Fuegian Andes. These three ice sheets are the Northern Patagonian Ice Field, the Southern Patagonian Ice Field, and the Darwin Cordillera Ice Field. The chapter includes also the most significant information available on the glaciations of the Chilean side of the Andes, along the same latitudinal belt.

Late Cenozoic Glaciations in Patagonia and Tierra del Fuego

Owing to their constant low temperatures, glacial ice and permafrost might contain the oldest nucleic acids and microbial cells on Earth, which could prove key to reconstructing past ecosystems and for the planning of missions to other planets. However, recent claims concerning viable cells and microbial nucleic acids obtained from ice- and permafrost cores from hundreds of thousands to millions of years old are not properly authenticated and the findings could be the result of contamination. Here, we discuss the processes that restrict the long-term survival of DNA and/or RNA molecules in ice and permafrost, and highlight sources of contamination that could result in false claims. Additionally, we present a set of precautions, controls and criteria to help ensure that future cultures and sequences are authentic.

Isolation of nucleic acids and cultures from fossil ice and permafrost

Nature's MutinyAfter the Ice AgeColonial CataclysmsClimate Change and the Health of NationsThe Medieval Warm PeriodIs the Temperature Rising?Climate and the Making of WorldsThe Frigid Golden AgeThe Palgrave Handbook of Climate HistoryLittle Ice AgeThe Little Ice AgeThe Crisis of the 14th CenturyTiny HabitsA Cold WelcomeGlacier Evolution in a Changing WorldThe Wim Hof MethodThe Great WarmingThe Little Ice AgeNature's MutinyWater on SandThe Little Ice AgeGlobal CrisisLittle Ice AgesThe Frigid Golden AgeBeautiful ThingsCultural consequences of the \"Little Ice Age\"The Little Ice AgeA Cold WelcomeA Cultural History of ClimateHistory and ClimateThe Incomparable ValleyA New Little Ice Age Has StartedNature's MutinyFamines During the ʻLittle Ice Ageʼ (1300-1800)Mechanisms of Natural Climate ChangeOur Subway BabyThe Rough Guide to Climate ChangeThe Little Ice AgeThe Iceberg in the Mist: Northern Research in Pursuit of a “Little Ice Age”Little Ice Age Glaciation in Alaska: A Record of Recent Global Climatic Change

The Little Ice Age

An assembly of stone slabs on an isolated butte in New Mexico collimates sunlight onto spiral petroglyphs carved on a cliff face. The light illuminates the spirals in a changing pattern throughout the year and marks the solstices and equinoxes with particular images. The assembly can also be used to observe lunar phenomena. It is unique in archeoastronomy in utilizing the changing height of the midday sun throughout the year rather than its rising and setting points. The construct appears to be the result of deliberate work of the Anasazi Indians, the builders of the great pueblos in the area.

https://science.sciencemag.org/content/sci/206/4416/283.full.pdf

A Unique Solar Marking Construct

Preface. Acknowledgments. Introduction. List of Participants. Color Plates. Biology. 1. Glacier Ecosystem and Biological Ice Core Analysis S. Kohshima, et al. 2. Isolation and Identification of Bacteria from Ancient and Modern Ice Cores B.C. Christner, et al. 3. Perspectives for DNA Studies on Polar Ice Cores A.J. Hansen, E. Willerslev. Climate and Paleoclimate. 4. Meteorological and Climatological Aspects of the Southern Patagonia Icefield, Patagonia J.F. Carrasco, et al. 5. Western Patagonia: A Key Area for Understanding Quaternary Paleoclimate at Southern Mid-Latitudes P.I. Moreno. 6. Late Pleistocene and Holocene Glacier Fluctuations in the Mendoza Andes, Argentina L.E. Espizua. Glaciology. 7. Current Knowledge of the Southern Patagonia Icefield G. Casassa, et al. 8. The Southern Patagonia Icefield Mass Balance J.C. Leiva. 9. Glacier Mass Balance and Climate in the South American Andes G. Kaser. 10. Ice Thickness Measurements on the Southern Patagonia Icefield A. Rivera, G. Casassa. Ice Coring. 11. Locating a Drilling Site on the Patagonian Icefield N. Gundestrup. 12. On the Potential to Retrieve Climatic and Environmental Information From Ice Core Sites Suffering Periodical Melt, with Specific Assessment of the Southern Patagonia Icefield V. Pohjola. 13. Argentine Program on Climate and Environmental Studies by Means of Ice Cores A.J. Aristarain. 14. Firn-Core Drilling Operational at Tyndall Glacier, Southern Patagonia Icefield M.-A. Godoi, et al. 15. First Results of a Palaeoatmospheric Chemistry and Climate Study of Cerro Tapado Glacier, Chile P. Ginot, et al. 16. Interpreting Climate Signals from a Shallow Equatorian Core: Antisana, Ecuador M.W. Williams, et al. 17. Potential Application of Methodologies for Studying Atmospheric Aerosols, in the Study of Climatic and Environmental Information from Ice Cores M. Prendez. Appendix. Glossary. Index.

The Patagonian icefields : a unique natural laboratory for environmental and climate change studies

Fast-neutron inelastic scattering has been studied in a number of elements by observation of the deexcitation gamma rays with a single-crystal NaI(Tl) spectrometer. Neutrons of energy 4.4\ifmmode\pm\else\textpm\fi{}0.1 Mev were used to bombard isotopically enriched scatterers of Ti, Cr, Ni, Zn, Ge, and W, and normal scatterers of Cl, Sr, Nb, Nd, Sm, and Gd. The low-lying levels in ${\mathrm{Ti}}^{47}$, I, and W are studied using neutron energies between 0.50 Mev and 1.45 Mev. Energies and relative yields of the gamma rays are given, and their assignment to various excited states is discussed. Previously unknown states were found in ${\mathrm{Ti}}^{48}$, ${\mathrm{Cr}}^{50}$, ${\mathrm{Zn}}^{64}$, ${\mathrm{Zn}}^{66}$, and ${\mathrm{Ge}}^{74}$.

Nuclear energy levels excited by fast neutrons

A conducting limiter brings about equilibrium of a toroidal plasma by anchoring magnetic field lines. Charge separation arising from the curvature effect can be short circuited by the limiter. This way of achieving equilibrium is not possible if the charge separation current exceeds the maximum ion saturation current to the limiter. Experiments with the Model C stellarator are consistent with this model. An observed instability is related to the loss of equilibrium due to the excess charge separation current.

Equilibrium of a Toroidal Plasma with a Conducting Aperture Limiter

A new ion cyclotron resonance heating system has been installed on the Model C stellarator. Use of low‐power rf during the entire Ohmic heating pulse shows that the density for optimum coupling is a factor of 1.5‐2 greater than that calculated from a simple theory. The variation of coupling with density and plasma radius is found to agree with theory. An anomalous second maximum in the coupling curve is found. At 1 MW power levels, little energy is transmitted around the ∪ bends by ion cyclotron waves, and it is necessary to have magnetic beaches adjacent to the Stix coil. Best heating is obtained with the least amount of magnetic beach. Use of a larger axial field gradient results in rapid loss of density under the Stix coil, with subsequent decrease in coupling and heating. The maximum ion temperature obtained in the ∪ bends is ∼ 550 eV, uniform to within 20%. A model is proposed in which cooling is dominated by particle losses and charge exchange, the particle loss rate being dependent on kTe.

Ion Cyclotron Heating in the Model C Stellarator

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