Toroid spectrometer for electron-ion collider

2020 ◽  
Vol 35 (34n35) ◽  
pp. 2044021
Author(s):  
Ivan Koop
Keyword(s):  
Magnetic Field ◽  
Solid Angle ◽  
Opposite Sign ◽  
Beam Axis ◽  
Magnetic Spectrometer ◽  
The Future ◽  
Momentum Resolution ◽  
The Magnetic Field

In this paper, we present two options of the toroid magnetic spectrometer dedicated to measure the energy and the polar and the azimuthal angles of the scattered from the ion’s nuclear electrons in the future electron-ion collider DERICA at JINR. These options differ by the opposite sign of the magnetic field. In one of the options, the toroid magnetic field bends electrons towards the collision line, while in the option with the inverted field a bent is done outwards from the beam axis. We show that the last case provides much larger useful fraction of a solid angle for detection of the scattered electrons. The momentum resolution of such a spectrometer is estimated.

Electrically driven vortices in a strong magnetic field

1988 ◽  
Vol 189 ◽  
pp. 553-569 ◽  
Author(s):  
Joël Sommeria
Keyword(s):  
Magnetic Field ◽  
Stokes Equations ◽  
Opposite Sign ◽  
Electric Pulse ◽  
Lateral Wall ◽  
Horizontal Layer ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
The Magnetic Field ◽  
Lower Plane

A steady isolated vortex is produced in a horizontal layer of mercury (of thickness a), subjected to a uniform vertical magnetic field. The vortex is forced by an electric current going from an electrode in the lower plane to the circular outer frame. The flow is investigated by streak photographs of small particles following the free upper surface, and by electric potential measurements. The agreement with the asymptotic theory for high values of the Hartmann number M is excellent for moderate electric currents. In particular all the current stays in the thin Hartmann layer of thickness a/M, except in the vortex core of horizontal extension a/M½. For higher currents, the size of the core becomes larger and depends only on the local interaction parameters. When the current is switched off, we measure the decay due to the Hartmann friction. A similar study is carried out for a vortex created by an initial electric pulse, and for a pair of vortices of opposite sign. For all these examples, the dynamics can be described by the two-dimensional Navier-Stokes equations with Hartmann friction, except in the vortex cores. Finally a vortex is produced near a lateral wall and a detachment of the boundary layer parallel to the magnetic field occurs, by which a second vortex of opposite sign is generated.

New scheme for computing the magnetic field resulting from a uniformly magnetized arbitrary polyhedron

Geophysics ◽  
1999 ◽  
Vol 64 (1) ◽  
pp. 70-74 ◽  
Author(s):  
D. Guptasarma ◽  
B. Singh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Arbitrary Shape ◽  
Numerical Evaluation ◽  
Solid Angle ◽  
New Approach ◽  
Polygonal Surface ◽  
Magnetic Poles ◽  
The Magnetic Field

The magnetic field at any point outside a uniformly magnetized polyhedron of arbitrary shape is obtained by adding the fields resulting from the effective free magnetic poles on each of the polygonal surfaces of the polyhedron. For each polygonal surface, the components of the field at the point of observation are expressed in terms of new line integrals around the edges of the polygon and the solid angle subtended by the polygon at the point of observation. The line integrals are standard elementary forms. This new approach makes the numerical evaluation of the magnetic fields for such models much simpler and faster than previously published methods.

The field boundary of two line currents immersed in a streaming plasma

1966 ◽  
Vol 25 (4) ◽  
pp. 761-768 ◽  
Author(s):  
C. Sozou ◽  
G. Loizou
Keyword(s):  
Magnetic Field ◽  
Opposite Sign ◽  
Conformal Transformations ◽  
Field Boundary ◽  
Finite Breadth ◽  
Arbitrary Line ◽  
The Magnetic Field

The cavity in which the magnetic field of two arbitrary line currents is confined by a streaming plasma which is assumed cold and perfectly conducting is investigated by using conformal transformations. When the magnetic field at the boundary is always directed in the same sense the finite breadth of the cavity at infinity depends only on the algebraic sum of the inducing currents and not their position. If the two line currents are of opposite sign the boundary magnetic field may change sign at two ‘pseudo-singularities’.

scholarly journals Why switchbacks may be related to solar granulation 

2021 ◽  
Author(s):  
Naïs Fargette ◽  
Benoit Lavraud ◽  
Alexis Rouillard ◽  
Victor Réville ◽  
Tai Phan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid Angle ◽  
Temporal Characteristic ◽  
Fast Fourier Transformation ◽  
Solar Granulation ◽  
Radial Magnetic Field ◽  
Solar Convection ◽  
Parker Spiral ◽  
The Magnetic Field ◽  
Characteristic Scales

<p>Parker Solar Probe data below 0.3 AU have revealed a near-Sun magnetic field dominated by Alfvénic structures that display back and forth reversals of the radial magnetic field. They are called magnetic switchbacks, they display no electron strahl variation consistent with magnetic field foldings within the same magnetic sector, and are associated with velocity spikes during an otherwise calmer background. They are thought to originate either at the photosphere through magnetic reconnection processes, or higher up in the corona and solar wind through turbulent processes.</p><p>In this work, we analyze the spatial and temporal characteristic scales of these magnetic switchbacks. We define switchbacks as a deviation from the parker spiral direction and detect them automatically through perihelia encounters 1 to 6. We analyze the solid angle between the magnetic field and the parker spiral both over time and space. We perform a fast Fourier transformation to the obtained angle and find a periodical spatial variation with scales consistent with solar granulation. This suggests that switchbacks form near the photosphere and may be caused, or at least modulated, by solar convection.</p>

scholarly journals The Stern-Gerlach experiment re-examined by an experimenter

2019 ◽  
Vol 50 (3) ◽  
pp. 15-19
Author(s):  
Horst Schmidt-Böcking
Keyword(s):  
Magnetic Field ◽  
Energy Resolution ◽  
Point Of View ◽  
Single Atom ◽  
Experimental Point ◽  
Momentum Resolution ◽  
The Magnetic Field

The historic Stern-Gerlach experiment (SGE), which was performed in 1922 in Frankfurt, is reviewed from an experimental point of view. It is shown that the SGE apparatus is a purely classical momentum spectrometer, in which the trajectories of particles are measured. With modern detection devices the passage of each single atom can be identified and its trajectory in the magnetic field precisely determined. At the time of their experiment Stern and Gerlach achieved a hitherto unprecedented momentum resolution corresponding to an energy resolution of one μeV.

I.—Focusing of Electron Beams in Crossed Static Electric and Magnetic Fields

1962 ◽  
Vol 66 (1) ◽  
pp. 1-19
Author(s):  
P. S. Farago
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Solid Angle ◽  
Scalar Potential ◽  
Charged Particles ◽  
Direction Parallel ◽  
Electric And Magnetic Fields ◽  
Double Focusing ◽  
The Magnetic Field ◽  
Focusing Properties

SynopsisIn a crossed static homogeneous electric and magnetic field charged particles describing trochoidal orbits in a plane perpendicular to the direction of the magnetic field are focused, but a beam emitted by a point source in a finite solid angle spreads out indefinitely in the direction parallel to the magnetic field. The essential characteristics of trochoidal orbits can be preserved if the superimposed magnetic and electric fields are two-dimensional and orthogonal, such as derived from a vector potential, say, Ax = A(y, z), Av = Az = O, and a scalar potential Ф(y, z)= const. A(y, z). The focusing properties of such a field combination depend on the distribution of the magnetic field only. Following some general considerations, specific examples of double focusing field distributions are given, and the electron motion in one of them is treated in detail.

Self-focusing of nonlinear ion-acoustic waves and solitons in magnetized plasmas

1985 ◽  
Vol 33 (2) ◽  
pp. 171-182 ◽  
Author(s):  
E. Infeld
Keyword(s):  
Magnetic Field ◽  
Nonlinear Waves ◽  
Acoustic Waves ◽  
Solid Angle ◽  
Ion Acoustic Waves ◽  
Weakly Nonlinear ◽  
Self Focusing ◽  
Long Wave ◽  
Weakly Nonlinear Waves ◽  
The Magnetic Field

The Zakharov-Kuznetsov equation describing Korteweg–de Vries waves and solitons in a strong, uniform magnetic field is rederived taking space stretching to be isotropic. This equation is then used to investigate nonlinear waves and solitons for long-wave instabilities. A solid angle of instability develops around the plane perpendicular to the magnetic field. For weakly nonlinear waves this angle is very narrow: widening as the amplitude of the nonlinear wave is increased. The soliton wave is unstable for all directions other than parallel to the field. Previous results of other authors, limited to solitons and perpendicular propagation are recovered. Calculations are illustrated by polar diagrams for the perturbations. Some broader implications are pointed out.

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