Top PDF Dynamics of plasma structures interacting with external and self-generated magnetic fields

Dynamics of plasma structures interacting with external and self-generated magnetic fields

Dynamics of plasma structures interacting with external and self-generated magnetic fields

Two large custom-made viewports (8 00 diameter window welded on a 10” flange) and a commercial viewport (6 00 view) installed on the east side of the vacuum chamber have been utilized for taking plasma pictures and spectra. More vacuum viewports with 8 00 or greater view were desired for the cameras and the spectroscopic system to gain a better access to the plasma. An economic viewport design has been devised since commercial vacuum viewports are available only up to ∼6” view and a custom-made viewport with larger view size would be expensive prohibiting multiple installations of such viewports. The viewport design (figure D.1 consists of a modified 10 00 Conflat flange, a viewport glass (Borofloat TM , 8.5 00 diameter, 11 mm thick), an O-ring to form a vacuum seal (Viton, AS568A no. 172), and several clamps to hold the glass in place. The clamps are to give only an initial vacuum seal. Once the chamber starts being pumped out, the pressure difference will build up across the glass window, press the O-ring against the flange, and form a vacuum seal. Several viewports have been constructed according to the design and successfully installed on the chamber.
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Dynamics of Self-Generated Magnetic Fields in Stagnation Phase and their Effects on Hot Spark Formation

Dynamics of Self-Generated Magnetic Fields in Stagnation Phase and their Effects on Hot Spark Formation

In fast ignition, megagauss-order magnetic fields ex- ert significant effects on the electron heat flux [5]. In laser plasmas, a magnetic field is not only generated by non-uniform laser irradiation but also by various instabil- ities such as collisionless and collisional Weibel instabili- ties [6, 7], thermal instability [8], and Rayleigh-Taylor in- stability [9]. When a laser irradiates a solid target, nonpar- allel temperature and density gradients appear due to the Rayleigh-Taylor (RT) instability [10]. The RT instability in the acceleration and the deceleration phases can be the major source of the magnetic field in imploded plasmas. The magnetic fields in the acceleration phase of the im- plosion are convected into the ablation front by the Nernst e ff ect [11]. These magnetic fields then penetrate further inward. The magnetic fields are amplified in the decelera- tion phase as well, where all the magnetic fields are com- pressed rapidly. Therefore, the magnetic fields become strong enough to influence the implosion process.
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Effect of external magnetic  fields on electron transfer and ion pairing dynamics at ferrocenyl alkane thiol SAM/solution interfaces

Effect of external magnetic fields on electron transfer and ion pairing dynamics at ferrocenyl alkane thiol SAM/solution interfaces

The redox behaviour of ferrocene alkane thiol self assembled monolayer modified electrodes in contact with aqueous perchlorate solutions both in the absence of and in the presence of an external magnetic field is examined using both electrochemical and gravimetric techniques The redox switching process involves an ET reaction involving the ferrocene/ferricinium redox transition coupled with an ion pairing step involving perchlorate ion. The voltammetric response recorded in the latter medium is irreversibly effected by the imposition of a static magnetic field of magnitude 0.5 T applied in a direction parallel to the electrode surface. The magnetic field dependence of the redox behaviour is attributed to structural changes in the monolayer arising from double layer effects involving changes in the spatial distribution of perchlorate counterions at the monolayer/solution interface, brought about by local convective stirring arising from the B field generated magnetohydrodynamic Lorenz body force.
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External and Internal Electromagnetic Exposures of Workers Near High Voltage Power Lines

External and Internal Electromagnetic Exposures of Workers Near High Voltage Power Lines

There has been a growing interest over the years in determining the safe exposure levels of people, mainly workers, and the general public, to power frequency electric and magnetic fields. Several organizations have developed standards and guidelines for such permissible exposure levels. By far, the most important organizations that have contributed to the establishment of these standards and guidelines are the Institute of Electrical and Electronics Engineers (IEEE) [1], and the International Commission on Non-Ionizing Radiation Protection (ICNIRP) [2]. There are other organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH) and The National Radiological Protection Board (NRPB) in the UK [3]. The permissible levels quoted in many countries refer to the permissible levels set by the IEEE standard or the ICNIRP guideline. Table 1, columns 3 to 5, show the list of external exposure limits for 60 Hz for the IEEE, ICNIRP and NRPB. Table 2 lists a summary of internal exposure limits for the same frequency.
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Effect of interchange instability on magnetic reconnection

Effect of interchange instability on magnetic reconnection

Although the results, obtained from two-fluid collisionless MHD models of the Hall reconnection, are impressive, the recent studies showed that the standard model of Hall recon- nection encounters some problems. Daughton et al. (2006) showed, for example, that there is a “significant inconsis- tence” between the results obtained from kinetic simulations and MHD simulations of the Hall reconnection. Particularly, they showed that the formation of a “bottleneck” for outflow electrons in the electron diffusion region can substantially re- duce the reconnection rate. Another problem is the effect of both embedded turbulence (as mentioned above) and internal plasmoid instability (e.g., Loureiro et al., 2007; Cassak and Shay, 2008; Daughton et al., 2009) within the reconnection layer, which leads to the formation of magnetic/ plasma is- lands (plasmoids). Recently, Huang et al. (2011) also showed that the transition to Hall reconnection may result in the for- mation of not a single X-point but several X-points in the reconnection layer that also lead to the formation of plas- moids, which link the Hall reconnection and turbulent recon- nection. The effect of plasmoids on reconnection rate will be discussed later.
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Long wavelength torsional modes of solar coronal plasma structures

Long wavelength torsional modes of solar coronal plasma structures

A cylindrical plasma structure embedded in a plasma of different properties is a popular model for several astrophysical objects, in particular coronal loops, plumes and jets in the solar corona. Such a structure is known to support a number of magnetohy- drodynamic (MHD) modes of oscillation, which can be divided into several classes according to their observational manifesta- tion. In low-β plasmas, typical for the solar corona, the modes of plasma cylinders are kink, sausage, longitudinal, ballooning and torsional (e.g. Edwin & Roberts 1983; Nakariakov & Verwichte 2005). In the most refined form the properties of these modes are seen in the case of the straight magnetic field, parallel to the axis of the cylinder. The first four modes are compressible (modi- fied slow or fast magnetoacoustic waves), while torsional modes (also known as rotational modes) are the only truly incompress- ible perturbations of the plasma (e.g., Van Doorsselaere et al. 2008) and propagate at the Alfvén speed, and hence should be considered as Alfvén waves. Torsional modes are propagating azimuthal (rotational) motions of the plasma, accompanied by the perturbations of the azimuthal component of the magnetic field. Also, torsional modes can be considered as an alternat- ing electric current aligned with the axis of the cylinder. Strictly speaking, in a plasma cylinder with a straight magnetic field, torsional waves are not modes, as perturbations of neighbouring magnetic surfaces are independent of each other and hence do not constitute a collective phenomenon. However, if the Alfvén speed is sufficiently uniform across the plasma structure and if the perturbations of the neighbouring magnetic surfaces are ex- cited in phase, torsional perturbations manifest themselves in observations as a quasi-collective mode-like perturbation. Thus,
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A Phenomenological Model for the Electromagnetic Origin of Mass in Particles, and Its Quantitative Application to the Electron, the Muon, the Proton, and the Neutron

A Phenomenological Model for the Electromagnetic Origin of Mass in Particles, and Its Quantitative Application to the Electron, the Muon, the Proton, and the Neutron

tices in the femtometer-size scale, in equilibrium with the surrounding fields (in which conditions such vortices might become stable is not clear, but a criterion will be proposed below). In the superconductor oscillator case, the external force in the presence of the external mag- netic fields triggers the motion of the loop and an in- duced supercurrent is generated, which traps energy and makes the loop reach dynamic equilibrium with the fields. In a microscopic scale such effects would take place due to fluctuations in electric and magnetic forces creating and then acting upon the stabilized vortices of charge. In the case the currents are resistanceless a magnetic energy would be trapped and the vortices would oscillate under some restoring force due to the fields around. The dis- cussion in Section 2 suggests that the quantity mass might again be defined for such vortices in a way analogous to the large-scale superconducting loop. What follows is the result of an extrapolation of the analysis of the Physics of the SEO, and its comparison with the known properties of subatomic particles, like the proton, the neutron, and also the electron and the muon. These particles would be considered as localized vortices with trapped energy, in equilibrium with the surrounding fields.
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IJARSE, Vol. No.3, Issue No.8, August 2014 ISSN-2319-8354(E)

IJARSE, Vol. No.3, Issue No.8, August 2014 ISSN-2319-8354(E)

The Hall co-efficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. It is a characteristic of the material from which the conductor is made, since its value depends on the type, number, and properties of the charge carriers that constitute the current. The Hall Effect comes about due to the nature of the current in a conductor. Current consists of the movement of many small charge carriers, typically electrons, holes, ions or all three. When such a magnetic field is absent, the charges follow approximately straight, 'line of sight' paths between collisions with impurities, phonons, etc. However, when a perpendicular magnetic field is applied, their paths between collisions are curved so that moving charges accumulate on one face of the material. This leaves equal and opposite charges exposed on the other face, where there is a scarcity of mobile charges.
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Long nuclear spin polarization decay times controlled by optical pumping in individual quantum dots

Long nuclear spin polarization decay times controlled by optical pumping in individual quantum dots

side a complex In-rich nanostructure, surrounded by the bar- rier material of a different composition 共GaAs兲. In contrast to bulk samples, an optical and electrical access to well- controlled electron states in the dot is readily available, this permitting us to shed further light on electron-nuclear spin dynamics by controlling the number, spin, and lifetime of the charge carriers on the dot. 12,13,16–19 A comprehensive theoret-

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The Development Of Fluxgate Magnetometer For Non-Destructive Measurement

The Development Of Fluxgate Magnetometer For Non-Destructive Measurement

Abstract. Non-Destructive measurements of ferromagnetic material and low frequency mag- netic flux disturbance require a highly sensitive and stable magnetic sensor with directional capa- bilities. A magnetometer based on fluxgate princi ple that meets the requirement had been deve- loped using a ferrite ring core. The ferrite ring core is excited by an excitation current source to achieve hysteresis condition. The pick up coil that is wound across the ring core will pick up the magnetic flux generated in the ring core. This sensing method is based on the conventional type of fluxgate magnetometer with detection of second harmonics by a phase sensitive detector. Major advantages of the fluxgate magnetometer are low cost, directional, easy to construct, reliable and rugged.
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A THEORETICAL STUDY OF TRIPLE QUANTUM WELL STRUCTURES UNDER EXTERNAL FIELDS

A THEORETICAL STUDY OF TRIPLE QUANTUM WELL STRUCTURES UNDER EXTERNAL FIELDS

Abstract: Using theoretical formalism of A. Large etal [Semicond. Sci. Technol. 2002], we have studied the shallow donor impurity in triple quantum well structures. We have used the effective mass approximation in the analysis of impurity related optical spectra. Our theoretically evaluated results for intra-donor transition energy and intra-donor magneto- absorption coefficients (arb. U) are in good agreement with the experimental data and also with other theoretical workers.

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Flux tubes in Nf = 2 + 1 QCD with external magnetic fields

Flux tubes in Nf = 2 + 1 QCD with external magnetic fields

on the lattice by considering the connected correlator sketched in Fig. 1, that has been originally in- troduced in Ref. [8, 9] and subsequently adopted in various works [10, 11]. The subscript stands for longitudinal, since we are considering the field component longitudinal with respect to the interquark separation. It has been observed that the transverse components of the color-electric field and all the color-magnetic field components are negligible within the flux tube [12]. We compute the field ex- actly at the mid-point of the QQ separation and at various transverse distances x t . In such a way, we
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A Device for Ligand-Free Single Cell Loading Using Magnetic Fields and Paramagnetic Microspheres

A Device for Ligand-Free Single Cell Loading Using Magnetic Fields and Paramagnetic Microspheres

In this study, we have demonstrated the successful use of varying magnetic fields to induce compressive forces via paramagnetic microspheres. Observation of a statistically significant increase in the Major axis length of the loaded cell nuclei as compared to the unloaded condition is noted. In addition, there are no statistically significant results in morphology changes of the cell nucleus due to the solenoid operation in cases where magnetic microspheres were not present upon the cellular surface. Thus, the changes observed were the result of direct compressive loading induced by the paramagnetic microspheres and not the result of thermal effects due to solenoid operation. This work has established the framework for a portable and economical device for application of loading conditions in biological environments to study cellular response under ligand-free conditions.
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Laboratory evidence of dynamo amplification of magnetic fields in a turbulent plasma

Laboratory evidence of dynamo amplification of magnetic fields in a turbulent plasma

Magnetic fields before the collision, and in the absence of any strong turbulence, are presumably Biermann battery fields pro- duced at the laser spots and then advected by the flow, as indeed is confirmed by FLASH simulations. In contrast, Fig. 4b, c— corresponding to a later stage of the turbulent plasma’s lifetime for the 10 and 5 ns pulse shapes, respectively—do indeed show strong features, indicative of increased fields strengths and altered morphology. These strong features are absent in single-flow experiments (see Supplementary Figure 8 in Supplementary Methods), suggesting that the interaction of the counter- propagating flows and subsequent development of turbulence is essential for magnetic field amplification. The reconstruction algorithm can also be applied to the images in Fig. 4b, c (see Fig. 4e, f); in the latter case, we obtain B rms ≈ 100 kG (see Sup-
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On the Possibility of Spontaneous Magnetic Field Observation in Turbulent Laser Plasma

On the Possibility of Spontaneous Magnetic Field Observation in Turbulent Laser Plasma

Figure 2 illustrates the first type of the experiments for the observation of the spontaneous magnetic field in turbulent plasma. The external strong regular magnetic field (~ 0.1 MG) is produced with help of powerful charge in the two special electrodes (see Figure 2a) 1 . The porous target is placed between the electrodes. The laser beam comes through the coil and absorbed in porous target. The hot turbulent plasma is produced. It contains the whirls and magnetic moments with arbitrary vectors of orientation in space (see
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Nonlinear equilibrium structure of thin currents sheets: influence of electron pressure anisotropy

Nonlinear equilibrium structure of thin currents sheets: influence of electron pressure anisotropy

sure. The fine structure of this profile of the current density is determined by the principal difference between the motion of ions and electrons inside TCS. Ions (with the Larmor ra- dius about CS thickness) are demagnetized near the neutral plane and are moving along open-ended orbits experiencing meandering type of motion near the neutral plane. The char- acteristic thickness of a “pure” ion current sheet (i.e. sheet with electrons serving only a cold neutralizing background) is about ion Larmor radius, and its profile is determined by non-harmonic oscillations of nonadiabatic ions in the region of strong magnetic field inhomogeneity. Otherwise electrons (with Larmor radius 50–100 times smaller) usually are mag- netized in the current sheet, and they move along drift orbits. Corresponding drift electron currents are [E×B], gradient and curvature ones. The third kind of particle drift depend- ing on the anisotropy of electron pressure absolutely predom- inates in a narrow region in the very center of the current sheet, where the curvature radii of the magnetic field lines are very small. The thickness of this region is proportional approximately to L(B n /B 0 ) 4/3 (Zelenyi et al., 2000), i.e. it
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Spectral modification of laser-accelerated proton beams by self-generated magnetic fields

Spectral modification of laser-accelerated proton beams by self-generated magnetic fields

B-field is a common feature in particle-in-cell (PIC) simulations; however the existence of a proton-focusing region of the B-field is a novel feature for these experimental parameters. This produces a broad spectral peak in the target normal spectrum. The measured signal at the peak is much higher than it is in the thicker target spectra at the same energy—the spectral modification also enhances the proton flux. Theoretical studies of underdense targets at higher intensities ( I ≈ 10 22 W cm −2 ) have indicated that proton-focusing B-fields can be formed [17, 18], although it has not been clear until now whether this could be realized or be significant at lower intensities (I ≈ 10 19 W cm −2 ) with planar solid foils. This is the first report of indications that there is a new regime of magnetically influenced TNSA in which highly non-Maxwellian spectra naturally occur.
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Study on Poloidal and Toroidal Electric Field Generations by Electron Cyclotron Heating in a Helical Plasma

Study on Poloidal and Toroidal Electric Field Generations by Electron Cyclotron Heating in a Helical Plasma

Poloidal and toroidal electric fields generated by electron cyclotron heating are studied in a helical plasma. A linearized Fokker-Planck equation is solved by the adjoint method, assuming a helically symmetric configuration for simplicity. It is found that the poloidal and toroidal electric fields are generated near the bottom of the magnetic ripple, and that the larger radial flux is enhanced in a helical plasma compared with that in a tokamak plasma.

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A structural-magnetic strain model for magnetostrictive transducers

A structural-magnetic strain model for magnetostrictive transducers

and 10a. For comparison, the magnetostriction given by (8) is plotted with experimental data in Fig- ures 9b and 10b. Recall that while the magnetic eld, magnetization and strains are time-dependent, data was collected at a suciently low frequency (0 : 7 Hz) to avoid AC losses and harmonic eects. It is observed in Figure 9 that some discrepancy occurs in both the strain and magnetostriction due to limitations in the quadratic model (8). The total strain provided by the dynamic model does, however, include the hysteresis observed in the experimental data. This is a signicant advantage over the modeled magnetostriction which is single-valued. This leads to the highly accurate model t observed in Figure 10 where the relation between the input eld H and the output strain e ( t;L ) at the rod tip is plotted.
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Post-processing scheme for modelling the lithospheric magnetic field

Post-processing scheme for modelling the lithospheric magnetic field

One can question if parts of the lithospheric field can be removed by our post-processing steps and contribute to the noise model. The lithospheric noise model derived is only a combination of spherical harmonics with some strong corre- lations between the Gauss coefficients. Therefore, there is no doubt that part of the true lithospheric magnetic field model can contribute to the noise model. It is, however, not possi- ble to estimate a priori what this part is because it clearly de- pends on both the noisy lithospheric field model on which the post-processing is applied and on the true lithospheric field we want to estimate. In order to test our scheme, we have first applied the processing on a synthetic data set built on a Gauss–Legendre grid where both the lithospheric field model and the noise are known. We used only the radial compo- nent of the field and verified that the noisy lithospheric field model derived from these data was contaminated by a noise corresponding exactly to Eq. (12). However, the full inver- sion process revealed that part of the lithospheric field was seen as noise. We also applied step 2 of our processing using a noise-free synthetic lithospheric field model and the noise model defined by Eq. (A12). Here again, despite a noise-free data set, the lithospheric field is partly interpreted as noise.
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