Simple Plasma Model Research Articles

Potential 67Ga radiopharmaceuticals for myocardial imaging: Tris(1-aryl-3-hydroxy-2-methyl-4-pyridinonato)gallium(III) complexes

A series of highly lipophilic complexes of 1-aryl-3-hydroxy-2-methyl-4-pyridinones with gallium(III)-67 has been evaluated in vitro and in vivo as potential radiopharmaceuticals. The pyridinones have different substituents at the para-position of the phenyl ring: R = H, CH 3, OCH 3 and NO 2. Biodistribution studies of 67Ga complexes have been carried out in rabbits, mice, rats and a dog. High heart uptake of the radionuclide has been shown in rabbits and the dog. The different biodistribution patterns in mice and rats indicate that there is a species difference in the biodistribution of these complexes. Rabbits and the dog show rapid heart uptake and blood clearance. The speciation of the Ga 3+ ion in vivo is simulated in vitro with a simple blood plasma model based on the available thermodynamic data.

Many-body effects in dense electron-hole plasma in InGaAs QWs with simple and complex valence band

High excitation magnetoluminescence spectra of highly homogeneous neutral electron-hole systems have been investigated in strained In x Ga 1− x As/GaAs and unstrained In 0.53Ga 0.47As/InP quantum wells (QW) with simple and complex valence band, respectively. A simple plasma model is found to describe satisfactorily the emission spectra from the dense EHP with large carrier temperature. The mass renormalization appears as a change of Landau level spacings. At n eh ≈ 10 12 cm −2, the interparticle interaction leads to ∼20% increase of the reduced mass micro −1 = m e −1 + m h −1 relative to its value in the empty ban renormalization strongly decreases with n eh. In the In 0.53Ga 0.47As/InP QW with small light-heavy hole subband splitting, Δ E v, there is an additional change in micro connected with the renormalization of Δ E v.

Modeling of whistler ray paths in the magnetosphere of Neptune

A three‐dimensional ray tracing program is used to investigate the propagation and dispersion of lightning‐generated whistlers in the magnetosphere of Neptune. A simple empirical magnetospheric plasma model based on observational constraints is used for the plasma density distribution, and an offset tilted dipole model is used for the magnetic field. Source positions for the whistlers are chosen along magnetic field lines withL< 3 in agreement with observations. Whistlers with frequencies of about 10 kHz generally propagate veiy near the resonance cone angle for most of the ray path, which produces dispersions considerably larger than those predicted for quasiparallel propagation. Dispersions computed using our “standard” plasma density model are over 30,000 s ✓Hz for “one‐hop” whistlers which is comparable to observed values. In general, the whistlers were found to propagate about 10° in magnetic longitude during one hop and to crossL shells. These results strongly support the existence of whistlers at Neptune. The large dispersions are attributed to the large cold plasma population at Neptune which leads to propagation very near the resonance cone angle for a large part of the ray path.

A Simple Plasma Model for the Description ofd-dFusion in Condensed Matter

AbstractA simple plasmalike model that describes the time behavior of the deuteron-deuteron (d-d) fusion reaction rate as a function of charging time is presented. When used to describe the experimental shape of d-d neutron production rates averaged over broad time intervals, the model gives reasonable agreement. The fusion rates obtained from this comparison are of the order of the magnitude of effects that could be expected by the combination of electron screening and fluctuation enhancement. The model allows predictions of the conditions under which d-d fusion neutrons in condensed matter might be observed and explains why, in many cases, no effects are observed.

TheE T -dependence of theJ/ψ suppression

We use the quantum mechanical approach of theJ/Ψ suppression in heavy ion collision to analyze theET-dependence of theJ/Ψ suppression. We find that within a simple quark-gluon plasma model with Lorentz invariant hydrodynamical evolution theET-dependence of theJ/Ψ suppression can be explained at least qualitatively.

Improvement of fusion reactivity and fusion power multiplication factor in the presence of fast ions

Improvement of fusion reactivity (〈σv〉) and fusion power multiplication factor ( Q) in the presence of fast ions has been investigated with the analytical solution of the velocity distribution function. Fast ions created by only NBI heating, only ICRF heating and a combination of NBI and ICRF heating are considered in a D-T plasma. The dependences of 〈σv〉 on the plasma temperature, the deposited power density, the electron density and the injected beam energy are clarified. Calculations of evaluating Q employ a simple plasma model in which the radial profiles of the plasma temperature and density are the same as those observed in recent experiments. 〈σv〉 and Q are enhanced by only NBI heating, the combined NBI and ICRF heating and only ICRF heating in this order under the same heating power. However, the increase in 〈σv〉 and Q for the former two methods is almost the same. In the presence of fast ions, the enhancement of 〈σv〉 and Q is larger than the increase in the plasma pressure.

Wave excitation downstream of the low‐β, quasi‐perpendicular bow shock

We interpret the low‐frequency wave observations of the AMPTE/IRM emission in the downstream region of a marginally supercritical, quasi‐perpendicular bow shock. A companion paper on ion heating comprehensively describes the corresponding plasma and wave magnetic field measurements. A simple model of the shocked plasma consisting of a background hydrogen magnetoplasma with anisotropic core protons permeated by a hotter dilute beam of anisotropic protons reproduces the basic features of the wave polarization and frequency spectra: wave activity below the proton cyclotron frequency, sometimes displaying a double‐humped structure, with unusual (in space plasmas outside the magnetosphere) dominance of (plasma frame) left‐hand‐polarized modes. The core and beam anisotropies stimulate electromagnetic (left‐hand) ion cyclotron waves in distinct spectral regions, whereas the large downstream Alfvén speed (with respect to the beam drift speed) precludes an efficient cyclotron resonant generation of the right‐hand magnetosonic modes.

Solution chemistry of gallium and indium 3-hydroxy-4-pyridinone complexes in vitro and in vivo

A series of complexes of several 3-hydroxy-2-methyl-4-pyridinones with gallium(III) and indium(III) have been characterized by potentiometric (glass electrode) titration. The effective formation constants of the various ligands for Ga 3+ at physiological pH are close to 10 31 . As a practical application of these data, comparative metal binding in a simple blood plasma model is simulated. This result is incorporated into the design of biodistribution experiments in mice using these ligands, their n-C 6 H 13 analogue, and l-mimosine

Comparison of ligands of differing denticity and basicity for the in vivo chelation of aluminium and gallium

Twenty-eight chelating ligands for aluminium, gallium and indium have been evaluated as binders of the M 3+ ions in a simple human blood plasma model. Effective formation constants (at pH 7.4) and values of pM (—log[M 3+]) were not found to be convenient tools for the comparison of all ligands under certain conditions. Speciation modelling allowed a direct comparison amongst ligands of the binding efficacy towards these metal ions under blood plasma conditions (50 μM transferrin sites, 0.1 M citrate, pH 7.4, 25°C). Applications of speciation computer modelling to animal studies are also discussed.

An analytical solution to the Boltzmann–Fokker–Planck equation for multi-component non-homogeneous plasmas

The previously obtained analytical solution to the Boltzmann equation for nonhomogeneous plasmas with relative large temperature and density gradients is generalized in the following sense. (i) The relatively simple Bhatnagar, Gross and Krook collision operator is replaced by the Fokker-Planck operator expressed in terms of relaxation rates (slowing down, energy exchange, etc.). (ii) The simple Lorentzian plasma model is replaced by a multi-component plasma model with realistic masses and temperatures.

Entropies and specific heats of liquid transition metals: one-component plasma model

A simple one-component plasma model is capable of describing the entropies and specific heats ( C v and C p ) of liquid 3d transition metals near the melting points. The agreement between theoretical and experimental values is remarkably good for the entropies.

The influence of a chromospheric magnetic field on the solar p- and f-modes

The influence of a chromospheric magnetic field on p- and f-mode frequencies is evaluated theoretically for a simple model of the solar plasma, consisting of a polytrope in the solar interior, above which is an isothermal atmosphere. The atmosphere is permeated by a horizontal magnetic field. Frequency changes and shifts in phase factors due to the presence of a magnetic atmosphere are calculated analytically in the long-wavelength limit, and numerically for arbitrary wavelength. The results reveal that, at low to moderate degree l, an increase in chromospheric magnetic field leads to a frequency increase for the n = 1 p-mode, whereas the overtones (n = 2, 3, etc.) suffer a frequency decrease. At high l, all the p-modes suffer a frequency decrease. 35 refs.

Anomalous absorption of 1- microm laser radiation by laser-produced plasmas.

We present the results of experiments where we have measured the absorption of laser light by plasmas generated by 20\char21{}120-psec duration pulses of Nd laser radiation incident upon solid targets at intensities exceeding ${10}^{14}$ W/${\mathrm{cm}}^{2}$. The results were obtained using box calorimetry, supported by ion calorimetry, ion probe data, and 2\ensuremath{\omega} calorimetry. We have found a marked asymmetry in the absorption for 120-psec pulses with irradiation geometry with the absorption dropping by 60% when the beam diverged at the target surface. The results were analyzed using a simple rigid plasma model and show that resonance absorption is not the dominant mechanism, but the absorption is caused by the presence of a narrow region near the critical surface having a strongly enhanced collision frequency most probably due to the presence of long-wavelength ion acoustic waves in the plasma.

Three dimensional analysis of design-modification effects on neutron streaming through the net divertor duct

In the design of the Next European Torus (NET), a poloidal divertor has been considered. The present work consists of two parts. In the first part, a three dimensional Monte Carlo analysis of neutron streaming through the NET divertor duct was performed using the MCNP code. The effect of design modifications was also examined. The analysis used a simplified plasma model (cylindrical), but simulated the divertor duct in full detail. The results indicated a streaming effect that depends on the configuration (angle) of the outside divertor plate. The second part of this work examined the effect that the divertor tile material has on streaming through the divertor duct. The materials examined included Stainless Steel 316L, carbon, beryllium, copper, tungsten, and molybdenum. The analyses showed that when total flux was compared, the streaming for all materials was similar; however, when one considered the fast flux component of the streaming neutrons, significant differences between materials emerged. In all cases molybdenum showed the highest fluxes. Finally, it is noted that, although the plasma model was simplistic (straight cylindrical model), this approach helped to identify the design and material aspects that dominate the streaming behavior.

Enhancement of fusion power multiplication factor

Enhancement of the fusion power multiplication factor, Q , has been investigated using a simple plasma model, in which the radial profiles of the plasma temperature and density or the fast-ion velocity distribution are the same as those observed in recent experiments. The break-even condition is relaxed by a peaked density profile, beam-plasma reactions, and the fast ions produced by ICRF heating at the second harmonic of deuterium in a D-T thermal plasma. The minimum n τ T required for break-even has also been lowered. Furthermore, it is possible to enhance Q through local thermal instability near the plasma center using a simple transport simulation, in which the profile of the plasma density does not change during the simulation and only the thermal conduction loss is considered. Finally, the operational plasma parameters for JT-60 in the n τ vs. T diagram have been investigated.

Resonant optical pumping of C III by XUV radiation from a CO2 laser produced plasma.

Resonant photoexcitation by XUV radiation from a CO2 laser produced plasma was investigated as a possible means to achieve laser action in the UV region. A carbon plasma containing CIII was pumped by Mn VI emission at 310.18 Aemanating from Mn plasma generated nearby. Both plasmas were produced by focused CO2 laser pulses onto solid targets. Population densities of pumped CIII ions in the upper levels, 4p1P° and 4f1F°, were estimated at 5×1011cm-3 and 4×1010cm-3, respectively. The optimum intensity of CO2 laser to obtain efficient pump radiation at 310.182A was approximately 500 MW/cm2. These results are explained by a simple hydrodynamic model of the laser-produced manganese plasma.

Characteristics of fusion reaction rate and neutron yield in deuterium plasma

Characteristics of the fusion reaction rate and the fusion neutron yield have been investigated taking into account the effect of fast ions. The dependences of the fusion reactivity (〈σν〉B) and normalized fusion reaction rate (QB) on the fast ion energy and target plasma temperature are clarified. The following reactions are considered: ( 1 ) D 0 → D + ( D ( d , n ) 3 He ) , ( 2 ) D 0 → D + ( D ( d , p ) T ) , ( 3 ) D 0 → T + ( T ( d , n ) 4 He ) , ( 4 ) T f → D + ( T ( d , n ) 4 He ) , ( 5 ) D 0 → H 3 e + ( H 3 e ( d , p ) 4 He ) , ( 6 ) H 3 e f → D + ( H 3 e ( d , p ) 4 He ) . The mutual relation of 〈σν〉B and QB for each reaction is also clarified. Furthermore, the fusion neutron yield (Fn) has been evaluated using a simple steady-state plasma model in which the radial profiles of the plasma temperature and density or the fast-ion velocity distribution are the same as those observed in recent experiments. The results of this model agree with those of the other calculational model. We have studied the following dependence for JT-60 plasma size: F n vs. n ¯ e , F n vs. τ E , F n vs. n ¯ e ( using ⁡ Kaye − Goldston or INTOR scaling ) , F n vs. n D / ( n D + n H ) , F n vs. E B , and F n vs. T i / T e .

Isothermal compressibility and sound velocity of liquid rare earth metals

The simple one-component plasma (OCP) model has been applied to the isothermal compressibilities of liquid rare earth metals. The calculated results are in fair agreement with those estimated from the long-wavelength limit of liquid structure factors and the well-known relation between the isothermal compressibility and the surface tension. The velocity of sound has been calculated by the Percus-Yevick (PY) phonon model using recently measured low-angle structure data. The OCP model appears to provide a fair description of the thermodynamic properties of liquid rare earth metals.

Scattering of electromagnetic waves by a nonuniform cylindrical plasma in the eikonal approximation

The scattering of a uniform plane electromagnetic wave form an inhomogeneous cylindrical plasma in the presence of an axial static magnetic field has been treated in the eikonal approximation. A simple expression is presented for the scattering function for ordinary wave scattering. This expression is expected to be a good approximation at small angles and for refractive indices close to unity ( omega 2<< omega p2). In order to show the accuracy of the eikonal approximation numerical comparisons with the exact results have been presented for the simple model of homogeneous plasma. Implications of the eikonal results in the plasma diagnostics have been discussed.

Prospects for Alpha Particle Heating in JET in the Hot Ion Regime

The prospects for alpha particle heating in JET are discussed. A computational model is developed to represent adequately the neutron yield from JET plasmas heated by neutral beam injection. This neutral beam model, augmented by a simple plasma model, is then used to determine the neutron yields and fusion Q-values anticipated for different heating schemes in future operation of JET with tritium. The relative importance of beam-thermal and thermal-thermal reactions is pointed out and the dependence of the results on, for example, plasma density, temperature, energy confinement and purity is shown. Full 1½-D transport code calculations, based on models developed for ohmic, ICRF and NBI heated JET discharges, are used also to provide a power scan for JET operation in tritium in the low density, high ion temperature regime. The results are shown to be in good agreement with the estimates made using the simple plasma model and indicate that, based on present knowledge, a fusion Q-value in the plasma centre above unity should be achieved in JET.