Hard X-Ray Diagnostic of Z-Pinch Discharges     

A. Robledo-Martinez  R. Aliaga-Rossel  I.H. Mitchell  J.P. Chittenden  A.E. Dangor  M.G. Haines 《Astrophysics and Space Science》1997,256(1-2):491-497

An experimental technique for the detection and time-resolved characterisation of hard X-radiation from a Z-pinch is described. The detectors employed consist of combinations of plastic scintillators and photomultipliers tubes coupled through optical fiber. The scintillators were fitted with thick aluminium and lead filters and cross filtering is then used to obtain the energy of the X-rays. It was found that the X-rays can reach energies of up to 4 MeV, much higher than the applied voltage. The observed radiation intensity varied with the disruption time lag.  相似文献   

Review of Inertial Confinement Fusion     

M.G. Haines 《Astrophysics and Space Science》1997,256(1-2):125-139

The physics of inertial confinement fusion is reviewed. The trend to short-wavelength lasers is argued, and the distinction between direct and indirect (soft X-ray) drive is made. Key present issues include the non-linear growth of Rayleigh–Taylor (R–T) instabilities, the seeding of this instability by the initial laser imprint, the relevance of self-generated magnetic fields, and the importance of parametric instabilities (stimulated Brillouin and Raman scattering) in gas-filled hohlraums. Experiments are reviewed which explore the R–T instability in both planar and converging geometry. The employment of various optical smoothing techniques is contrasted with the overcoating of the capsule by gold coated plastic foams to reduce considerably the imprint problem. The role of spontaneously generated magnetic fields in non-symmetric plasmas is discussed. Recent hohlraum compression results are presented together with gas bag targets which replicate the long-scale-length low density plasmas expected in NIF gas filled hohlraums. The onset of first Brillouin and then Raman scattering is observed. The fast ignitor scheme is a proposal to use an intense short pulse laser to drill a hole through the coronal plasma and then, with laser excited fast electrons, create a propagating thermonuclear spark in a dense, relatively cold laser-compressed target. Some preliminary results of laser hole drilling and 2-D and 3-D PIC simulations of this and the > 10⁸ Gauss self-generated magnetic fields are presented. The proposed National Ignition Facility (NIF) is described.  相似文献   

A phase-front method - III. Acoustic waves, P- and S-waves     

A. J. Haines 《Geophysical Journal International》1984,77(1):65-103

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Palaeozoic synorogenic sedimentation in central and northern Australia: A review of distribution and timing with implications for the evolution of intracontinental orogens   总被引：1，自引：1，他引：0  

P. W. Haines  M. Hand  M. Sandiford 《Australian Journal of Earth Sciences》2013,60(6):911-928

The Palaeozoic Alice Springs Orogeny was a major intraplate tectonic event in central and northern Australia. The sedimentological, structural and isotopic effects of the Alice Springs Orogeny have been well documented in the northern Amadeus Basin and adjacent exhumed Arunta Inlier, although the full regional extent of the event, as well as lateral variations in timing and intensity are less well known. Because of the lack of regional isotopic data, we take a sedimentological approach towards constraining these parameters, compiling the location and age constraints of inferred synorogenic sedimentation across a number of central and northern Australian basins. Such deposits are recorded from the Amadeus, Ngalia, Georgina, Wiso, eastern Officer and, possibly, Warburton Basins. Deposits are commonly located adjacent to areas of significant basement uplift related to north‐south shortening. In addition, similar aged orogenic deposits occur in association with strike‐slip tectonism in the Ord and southern Bonaparte Basins of northwest Australia. From a combination of sedimentological and isotopic evidence it appears that localised convergent deformation started in the Late Ordovician in the eastern Arunta Inlier and adjacent Amadeus Basin. Synorogenic style sedimentation becomes synchronously widespread in the late Early Devonian and in most areas the record terminates abruptly close to the end of the Devonian. A notable exception is the Ngalia Basin in which such sedimentation continued until the mid‐Carboniferous. In the Ord and Bonaparte Basins there is evidence of two discrete pulses of transcurrent activity in the Late Devonian and Carboniferous. The sedimentological story contrasts with the isotopic record from the southern Arunta Inlier, which has generally been interpreted in terms of continuous convergent orogenic activity spanning most of the Devonian and Carboniferous, with a suggestion that rates of deformation increased in the mid‐Carboniferous. Either Carboniferous sediments have been stripped off by subsequent erosion, or sedimentation outpaced accommodation space and detritus was transported elsewhere.  相似文献   

Microchemistry and microstructures of hydrothermally altered shock-metamorphosed basement gneiss,Woodleigh impact structure,Southern Carnarvon Basin,Western Australia     

A. Y. Glikson  S. Eggins  S. D. Golding  P. W. Haines  R. P. Iasky  T. P. Mernagh 《Australian Journal of Earth Sciences》2013,60(4-5):555-573

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Keene Basalt,northwest Officer Basin,Western Australia: tectonostratigraphic setting and implications for possible submarine mineralisation     

F. Pirajno  P. W. Haines  R. M. Hocking 《Australian Journal of Earth Sciences》2013,60(6):1013-1022

GSWA Lancer 1, drilled in the northwest Officer Basin, intersected 49 m of tholeiitic basalt lava flows between depths of 527 and 576 m. These lavas have been named the Keene Basalt and were erupted during deposition of the shallow-marine Kanpa Formation, a mixed carbonate – siliciclastic succession in the Neoproterozoic Buldya Group. No direct dating of the Keene Basalt has been undertaken. Maximum depositional age constraints for the enclosing Kanpa Formation are provided by youngest concordant detrital zircon ages of 779±6 Ma for sandstone 19 m below the basalt, and 725±11 Ma for sandstone at the top of the Kanpa Formation in another drillhole. Correlation of the Kanpa Formation with the Burra Group of the Adelaide Rift Complex on palaeontological and chemostratigraphic grounds suggests an age older than 700 Ma. Limited geochemical data indicate that the Keene Basalt is of continental origin and shows a close similarity to mafic dykes near Mingary in South Australia. Petrographic and XRD analyses show that the Keene Basalt has been hydrothermally altered by interaction with seawater, and locally contains disseminated sulfides. Massive and disseminated sulfide mineralisation, similar to that of submarine systems, may exist in this tectonostratigraphic setting in the northwest Officer Basin.  相似文献   

Self-consistent treatment of tidal variations in the geocenter for precise orbit determination     

Shailen D. Desai  Willy Bertiger  Bruce J. Haines 《Journal of Geodesy》2014,88(8):735-747

We show that the current levels of accuracy being achieved for the precise orbit determination (POD) of low-Earth orbiters demonstrate the need for the self-consistent treatment of tidal variations in the geocenter. Our study uses as an example the POD of the OSTM/Jason-2 satellite altimeter mission based upon Global Positioning System (GPS) tracking data. Current GPS-based POD solutions are demonstrating root-mean-square (RMS) radial orbit accuracy and precision of \({<}1\)  cm and 1 mm, respectively. Meanwhile, we show that the RMS of three-dimensional tidal geocenter variations is \({<}6\)  mm, but can be as large as 15 mm, with the largest component along the Earth’s spin axis. Our results demonstrate that GPS-based POD of Earth orbiters is best performed using GPS satellite orbit positions that are defined in a reference frame whose origin is at the center of mass of the entire Earth system, including the ocean tides. Errors in the GPS-based POD solutions for OSTM/Jason-2 of \({<}4\)  mm (3D RMS) and \({<}2\)  mm (radial RMS) are introduced when tidal geocenter variations are not treated consistently. Nevertheless, inconsistent treatment is measurable in the OSTM/Jason-2 POD solutions and manifests through degraded post-fit tracking data residuals, orbit precision, and relative orbit accuracy. For the latter metric, sea surface height crossover variance is higher by \(6~\hbox {mm}^{2}\) when tidal geocenter variations are treated inconsistently.  相似文献   

New insights into the structure of early-type galaxies: the Photometric Plane at z∼ 0.3     

F. La Barbera  G. Covone  G. Busarello  M. Capaccioli  C. P. Haines  A. Mercurio  P. Merluzzi 《Monthly notices of the Royal Astronomical Society》2005,358(4):1116-1132

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On the production of hard X-rays in solar flares     

G. M. Simnett  M. G. Haines 《Solar physics》1990,130(1-2):253-263

The problem of producing the hard X-ray burst at the onset of solar flares may be thought of in terms of the problem of producing the non-thermal electrons which emit the X-rays via bremsstrahlung. Electron acceleration to relativistic energies without similar ion acceleration is difficult to achieve, even in an ad hoc theoretical model. Yet from global energetic considerations, it is not feasible to accelerate the electrons as a minor constituent of the total energetic particle population. Therefore, it is necessary to invoke a more sophisticated process for the electron acceleration. In this paper we describe a mechanism for achieving this via an initial acceleration of a neutralized ion beam. When such a beam impacts the chromosphere, the electrons start to scatter while the ions continue downwards, rapidly setting up an electric field which is either cancelled by the inflow of background chromospheric electrons or results in the runaway acceleration of beam electrons. In the former case the result is simply heating, whereas in the latter case much of the ion kinetic energy is transferred into electron kinetic energy. The final electron energy may be similar to the typical energy of the ions. The electrons that are accelerated are those in the neutral beam that experience an electric field greater than the critical Dreicer field. Thus there will be a low-energy cut-off to the electron spectrum which overcomes the well-known energetics problem at low energies with certain other spectral forms.  相似文献   

Seismic tomography of the Tongariro Volcanic Centre, New Zealand     

D. P. Rowlands  R. S. White  A. J. Haines 《Geophysical Journal International》2005,163(3):1180-1194

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