Microwave electronic properties of metal-ammonia solutions

Breitschwerdt, K.G.; Radscheit, H.

doi:10.1021/j100593a022

Cited by 8 publications

(12 citation statements)

References 1 publication

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“…[173], where the author used a spherically symmetric model of the Galaxy and considered only baryons and stars for the calculation of the gravitational potential. Later [174] presented an extensive discussion of the hydrodynamics of CR driven winds: dark matter was included and a realistic geometry of the wind was considered, in which the launch takes place at some distance from the galactic disc and proceeds in a roughly cylindrical symmetry out to a distance of about ∼ 15 kpc, where the flow opens up into a spherical shape. The calculations of [174] treated CRs as a fluid, hence no information on the spectrum of CRs was retained.…”

Section: Cr Driven Galactic Windsmentioning

confidence: 99%

“…Later [174] presented an extensive discussion of the hydrodynamics of CR driven winds: dark matter was included and a realistic geometry of the wind was considered, in which the launch takes place at some distance from the galactic disc and proceeds in a roughly cylindrical symmetry out to a distance of about ∼ 15 kpc, where the flow opens up into a spherical shape. The calculations of [174] treated CRs as a fluid, hence no information on the spectrum of CRs was retained. The important role of wave damping in the wind region was also discussed in [174], although only in the simplified case of a spherical outflow.…”

Section: Cr Driven Galactic Windsmentioning

confidence: 99%

“…The calculations of [174] treated CRs as a fluid, hence no information on the spectrum of CRs was retained. The important role of wave damping in the wind region was also discussed in [174], although only in the simplified case of a spherical outflow. As mentioned above, [174] assumed that the wind is launched some distance away from the disc of the Galaxy and this assumption raises the issue of what happens in the region between the disc and the base of the wind, a problem of both mathematical and physical importance [175].…”

Section: Cr Driven Galactic Windsmentioning

confidence: 99%

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Selected Topics in Cosmic Ray Physics

Aloisio

Blasi

Mitri

et al. 2018

Multiple Messengers and Challenges in Astroparticle Physics

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The search for the origin of cosmic rays is as active as ever, mainly driven by new insights provided by recent pieces of observation. Much effort is being channelled in putting the so called supernova paradigm for the origin of galactic cosmic rays on firmer grounds, while at the highest energies we are trying to understand the observed cosmic ray spectra and mass composition and relating them to potential sources of extragalactic cosmic rays. Interestingly, a topic that has acquired a dignity of its own is the investigation of the transition region between the galactic and extragalactic components, once associated with the ankle and now increasingly thought to be taking place at somewhat lower energies. Here we summarize recent developments in the observation and understanding of galactic and extragalactic cosmic rays and we discuss the implications of such findings for the modelling of the transition between the two.

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Section: Cr Driven Galactic Windsmentioning

confidence: 99%

Section: Cr Driven Galactic Windsmentioning

confidence: 99%

Section: Cr Driven Galactic Windsmentioning

confidence: 99%

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Selected Topics in Cosmic Ray Physics

Aloisio

Blasi

Mitri

et al. 2018

Multiple Messengers and Challenges in Astroparticle Physics

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“…Cosmic ray driven winds can attain high velocities (see e.g. Breitschwerdt et al 1991;Reuter et al 1994;Newman et al 2012) and could magnetize a galactic halo and the IGM quiet fast (Kronberg et al 1999) or even the largest voids ). The addition of an explicit model for galactic winds or a cosmic ray energy budget and pressure component into our simulations could cause additional gas motions.…”

Section: Magnetic Amplitude and Filling Factorsmentioning

confidence: 99%

Strong magnetic fields and large rotation measures in protogalaxies from supernova seeding

Beck

Dolag

Lesch

et al. 2013

Monthly Notices of the Royal Astronomical Society

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We present a model for the seeding and evolution of magnetic fields in protogalaxies. Supernova (SN) explosions during the assembly of a protogalaxy self-consistently provide magnetic seed fields, which are subsequently amplified by compression, shear flows and random motions. Our model explains the origin of strong magnetic fields of µG amplitude within the first starforming protogalactic structures shortly after the first stars have formed. We implement the model into the MHD version of the cosmological N-body / SPH simulation code GADGET and we couple the magnetic seeding directly to the underlying multi-phase description of star formation. We perform simulations of Milky Way-like galactic halo formation using a standard ΛCDM cosmology and analyse the strength and distribution of the subsequent evolving magnetic field. Within starforming regions and given typical dimensions and magnetic field strengths in canonical SN remnants, we inject a dipole-shape magnetic field at a rate of ≈10 −9 G Gyr −1 . Subsequently, the magnetic field strength increases exponentially on timescales of a few ten million years within the innermost regions of the halo. Furthermore, turbulent diffusion, shocks and gas motions transport the magnetic field towards the halo outskirts. At redshift z≈0, the entire galactic halo is magnetized and the field amplitude is of the order of a few µG in the center of the halo and ≈10 −9 G at the virial radius. Additionally, we analyse the intrinsic rotation measure (RM) of the forming galactic halo over redshift. The mean halo intrinsic RM peaks between redshifts z≈4 and z≈2 and reaches absolute values around 1000 rad m −2 . While the halo virializes towards redshift z≈0, the intrinsic RM values decline to a mean value below 10 rad m −2 . At high redshifts, the distribution of individual starforming and thus magnetized regions is widespread. This leads to a widespread distribution of large intrinsic RM values. In our model for the evolution of galactic magnetic fields, the seed magnetic field amplitude and distribution is no longer a free parameter, but determined self-consistently by the star formation process occuring during the formation of cosmic structures. Thus, it provides a solution to the seed field problem.

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“…to propose an equilibrium model for the interpretation of the conduction behaviour of MAS, assuming a proper chemical equilibrium between solvated electrolytelike electrons es-of low mobility and unsolvated free electrons e,-of high mobility. These observations are: ( I ) electrons photoinjected from a cathode into liquid ammonia exist in two different states, which exhibit low and high mobility (0.03 and 2000 cm2 V -l s-l) (9) and which might be characterized as solvated and free electrons, and (2) the absorption spectrum of solvated electrons persists still in higher concentrated solutions, i.e. that solvated electrons are present in solutions of metallic character (10).…”

Section: O N Peut Decrire La Conductivitt Electrique Des Solutions Mementioning

confidence: 99%

Equilibrium model for the interpretation of the conduction properties of metal–ammonia solutions

Hahne¹,

Krebs²,

Schindewolf³

1977

Can. J. Chem.

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Can. J. Chem. 55.221 l(1977). Recently we (1) presented experimental data about the electrical conductivity of metalammonia solutions (MAS) in the temperature and pressure range from 240 to 420 K and 200 to 1000 bar, respectively. As shown in Fig. 1, in which the equivalent conductance A at collstallt pressure (A = o / c (R-I cm2 mol-I); o specific conductivity (R-I c n~-l ) , c molar concentration (mol/cm3)) is plotted rs. molar concentration with temperature as parameter, the steep increase of the conductivity is shifted to smaller concentrations with increasing temperature; pressure increase on the other hand leads to a shift to higher concentrations. The electrical conductivity o f metal-ammonia solutions can be described by an equilibrium o f solvated electrons o f low mobility and o f free electrons o f high mobility. With proper choice o f the equilibrium constant and itsNo matter what the conduction mecha~lism in these solutions is and how the nonn~etal-metal transition (NMT) is defined the data suggest that this transition is favoured by temperature increase and opposed by pressure increase.For the interpretation of the NMT in MAS two contrasting theories were presented by Cohen and Jortner (2) and Mott (3), respectively, based on the percolation model and on the concept of the Anderson transition. Although the authors gave a series of arguments to support their concepts it seemed that no general agreement is obtained on the nature of the NMT and the conduction mechanism in moderate to high coilcentrated solutions. Only for the dilute range (c < 0.05 mol/f or 0.1 mol"7, metal (mpiu)) in wh~ch the equivalent conductance varies only slightly with concentration (A = 500-1000 !X1 cn12 mol-' at 240 K) is it not doubted that the electrical current is carried by individual moving solvated electrons and metal cations (4).In the intermediate range (0.5-2 mol/C or 1-4 mpm. depending on temperature) with the beginning steep conduction increase and the still unexplained maxima of the posit~ve temperature coefficient (5) and the negat~ve pressure coefficient (6) of the conductiv~ty (see also Fig. 3), seiuiconduction is assumed. This is supported by the peculiar temperature dependence of the thermopower (7, 8) (see also Fig. 4) which in the intermediate range decreases with temperature as is to be expected for activated transport (3), whereas in lower and higher concentrated MAS it increases with temperature.Besides a more or less quantitative description of the conduction behaviour of the MAS at normal temperature and pressure, no explanation was given or could be given on the basis of the percolation model or the Anderson concept for the observed shifts of the N M T with temperature and pressure.Two experimental observations prompted us Can. J. Chem. Downloaded from www.nrcresearchpress.com by 54.245.55.244 on 05/10/18For personal use only.

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Microwave electronic properties of metal-ammonia solutions

Cited by 8 publications

References 1 publication

Selected Topics in Cosmic Ray Physics

Selected Topics in Cosmic Ray Physics

Strong magnetic fields and large rotation measures in protogalaxies from supernova seeding

Equilibrium model for the interpretation of the conduction properties of metal–ammonia solutions

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