scholarly journals SIMULATION OF THE COMPENSATION OF A HIGH-CURRENT ION BEAM BY AN ELECTRON BEAM IN A CUSP MAGNETIC SYSTEM

2021 ◽  
pp. 122-127
Author(s):  
I.N. Onishchenko ◽  
O.V. Fedorovskaya
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Space Charge ◽  
Longitudinal Magnetic Field ◽  
Ion Beam ◽  
Zero Magnetic Field ◽  
High Current ◽  
Field Lines ◽  
Dynamics Of Particles ◽  
The Magnetic Field

The results of 2.5D-simulation of the dynamics of particles of a high-current ion beam moving in a magnetic field of acute-angled geometry (cusp), compensated in charge and current by an electron beam injected along the radius onto the axis from the periphery, uniformly in azimuth, are presented. The influence of own space charge fields and polarization fields on the dynamics of ions is clarified. It is shown that at high densities of the electron and ion beams, the electron beam injected into the cusp together with the ion beam, moving along the magnetic field lines, drags the ion beam away from the axis to the periphery into the region of zero magnetic field. At the exit from the cusp, the electron beam injected along the radius onto the axis drifts along the axis in a uniform magnetic field, while the ion beam performs oscillatory motion by radius in the crossed the electric field of the electron beam space charge and the longitudinal magnetic field.

scholarly journals Experimental investigation of ion beam transport in laser initiated plasma channels

2002 ◽  
Vol 20 (4) ◽  
pp. 559-563 ◽  
Author(s):  
D. PENACHE ◽  
C. NIEMANN ◽  
A. TAUSCHWITZ ◽  
R. KNOBLOCH ◽  
S. NEFF ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heavy Ions ◽  
Plasma Channel ◽  
Ion Beam ◽  
Heavy Ion ◽  
High Current ◽  
Beam Transport ◽  
Electrode Gap ◽  
Discharge Gap ◽  
The Magnetic Field

The aim of the presented experiments is to study the transport of a heavy ion beam in a high-current plasma channel. The discharge is initiated in NH3 gas at pressures between 2 and 20 mbar by a line-tuned CO2 laser. A stable discharge over the entire electrode gap (0.5 m) was achieved for currents up to 60 kA. Concerning the ion beam transport, the magnetic field distribution inside the plasma channel has to be known. The ion-optical properties of the plasma channel have been investigated using different species of heavy ions (C, Ni, Au, U) with 11.4 MeV/u during six runs at the Gesellschaft für Schwerionenforschungs-UNILAC linear accelerator. The high magnetic field allowed the accomplishment of one complete betatron oscillation along the discharge channel. The results obtained up to now are very promising and suggest that, by scaling the discharge gap to longer distances, the beam transport over several meters is possible with negligible losses.

PERTURBATION THEORY FOR THE ALFVÉN WAVE

1995 ◽  
Vol 09 (22) ◽  
pp. 2857-2898 ◽  
Author(s):  
Z. YOSHIDA ◽  
S.M. MAHAJAN
Keyword(s):  
Magnetic Field ◽  
Perturbation Theory ◽  
Electron Beam ◽  
Continuous Spectrum ◽  
Point Spectrum ◽  
Alfven Wave ◽  
Wave Number ◽  
Ambient Magnetic Field ◽  
Field Lines ◽  
The Magnetic Field

The Alfvén wave is the dominant low frequency transverse mode of a magnetized plasma. The Alfvén wave propagates along the magnetic field, and displays a continuous spectrum even in a bounded plasma. This is essentially due to the degeneracy of the wave characteristics, i.e. the frequency (ω) is primarily determined by the wave number in the direction parallel to the ambient magnetic field (k||) and is independent of the perpendicular wavenumbers. The characteristics, that are the direction along which the wave energy propagates, are identical to the ambient magnetic field lines. Therefore, the spectral structure of the Alfvén wave has a close relationship with the geometric structure of the magnetic field lines. In an inhomogeneous plasma, the Alfvén resonance (ω−cAk||=0; cA is the phase velocity of the Alfvén wave) constitutes a singularity for the defining wave equation; this results in a singular eigenfunction corresponding to the continuous spectrum. The aim of this review is to present an overview of the perturbation theory for the Alfvén wave. Emphasis is placed on those perturbations of the continuous spectrum which lead to the creation of point spectra. Such qualitative changes in the spectrum are relevant to many plasma phenomena. The first category of perturbations consists of nonideal effects such as the finite conductivity, kinetic effects arising from the finite electron inertia, and finite gyroradius. These effects add singular perturbations to the mode equation, and modify the spectrum dramatically. These modification, viz. the conversion of the continuous to the point spectrum, can lead to interesting physical phenomenon. A case in point is that of an electron beam propagating in a plasma which Cherenkov emits a left-hand circularly polarized Alfvén wave. The helicity of the ambient magnetic field imparts a frequency shift to the eigenmodes changing the critical velocity for Cherenkov emission. It, then, becomes possible for a sub-Alfvénic electron beam to excite a nonsingular Alfvén wave corresponding to a point spectrum. The second category comprises of geometric perturbations associated with higher dimensional inhomogeneity of the ambient field. Forbidden bands occur when a periodic modulation is applied. In a chaotic magnetic field, the weak localization of the wave occurs, resulting in a point spectrum.

scholarly journals Emission Features and Structure of an Electron Beam versus Gas Pressure and Magnetic Field in a Cold-Cathode Coaxial Diode

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 248
Author(s):  
Gennady Mesyats ◽  
Vladislav Rostov ◽  
Konstantin Sharypov ◽  
Valery Shpak ◽  
Sergey Shunailov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Runaway Electrons ◽  
High Current ◽  
Emission Mechanism ◽  
Explosive Emission ◽  
Fast Electrons ◽  
Atmospheric Air ◽  
Emission Surface ◽  
The Magnetic Field

The structure of the emission surface of a cold tubular cathode and electron beam was investigated as a function of the magnetic field in the coaxial diode of the high-current accelerator. The runaway mode of magnetized electrons in atmospheric air enabled registering the instantaneous structure of activated field-emission centers at the cathode edge. The region of air pressure (about 3 Torr) was determined experimentally and via analysis, where the explosive emission mechanism of the appearance of fast electrons with energies above 100 keV is replaced by the runaway electrons in a gas.

scholarly journals Simulation of propagating a proton beam in a reactor

1997 ◽  
Vol 15 (1) ◽  
pp. 151-165 ◽  
Author(s):  
K. Niu
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Proton Beam ◽  
High Speed ◽  
Electrostatic Force ◽  
Ion Beam ◽  
Leading Edge ◽  
Small Radius ◽  
Field Energy ◽  
The Magnetic Field

One of the difficulties of light ion beam fusion is to propagate the beam in the reactor cavity and to focus the beam on the target. The light ion beam has some local divergence angle because there are several causes for divergence at the diode. The ion beam propagates with a speed of one tenth of light speed. With this high speed, the leading edge of the ion beam cannot be charge-neutralized due to the delay of neutralization by the inertia of thermal electrons in the background plasma. The electrostatic force induced by this mechanism at the leading edge causes the beam divergence during propagation. To confine the beam in a small radius during propagation, the magnetic field must play a role. Here the electron beam is proposed to be launched simultaneously with the launch of a proton beam. If the electron beam has the excess current, the beam induces the magnetic field in the negative azimuthal direction, which confines the ion beam in a small radius by the electrostatic field, as well as the electron beam by the Lorentz force. The metal guide around the beam path helps the beam confinement and reduces the total amount of magnetic field energy induced by the electron current. Simulation shows that the proton beam with the comoving electron beam propagates in a small radius confined in the metal guide.

scholarly journals Condition for magnetic insulation of the electron beam in a rod-pinch diode

2003 ◽  
Vol 21 (2) ◽  
pp. 273-277 ◽  
Author(s):  
A.V. KIRIKOV ◽  
S.YA. BELOMYTTSEV ◽  
V.V. RYZHOV ◽  
I.YU. TURCHANOVSKY ◽  
V.P. TARAKANOV
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
High Speed ◽  
Electron Flow ◽  
Naval Research ◽  
High Current ◽  
Magnetic Insulation ◽  
Momentum Fluxes ◽  
The Magnetic Field ◽  
Theoretical Results

A condition for the transition of the electron beam produced in a coaxial rod-pinch diode to the mode of magnetic insulation has been established from the law of conservation of particle and field momentum fluxes. The magnetic field of the external current has been shown to contribute twice as much to magnetic insulation of the beam as the magnetic field of the electron beam self-current. Based on the relations derived, a model has been constructed for magnetic insulation of the electron flow in high-current rod-pinch diodes, which are used for radiography of high speed phenomena. The obtained theoretical results agree well with the results of numerical calculations and with experimental data gained at the Naval Research Laboratory (USA).

scholarly journals Alfvén waves in the near-PSBL lobe: Cluster observations

2006 ◽  
Vol 24 (3) ◽  
pp. 1001-1013 ◽  
Author(s):  
T. Takada ◽  
R. Nakamura ◽  
W. Baumjohann ◽  
K. Seki ◽  
Z. Vörös ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Ion Beam ◽  
Low Frequency ◽  
Poynting Flux ◽  
Field Fluctuations ◽  
The Rich ◽  
Field Lines ◽  
The Waves ◽  
The Magnetic Field ◽  
Low Frequency Waves

Abstract. Electromagnetic low-frequency waves in the magnetotail lobe close to the PSBL (Plasma Sheet Boundary Layer) are studied using the Cluster spacecraft. The lobe waves show Alfvénic properties and transport their wave energy (Poynting flux) on average toward the Earth along magnetic field lines. Most of the wave events are rich with oxygen (O+) ion plasma. The rich O+ plasma can serve to enhance the magnetic field fluctuations, resulting in a greater likelihood of observation, but it does not appear to be necessary for the generation of the waves. Taking into account the fact that all events are associated with auroral electrojet enhancements, the source of the lobe waves might be a substorm-associated instability, i.e. some instability near the reconnection site, or an ion beam-related instability in the PSBL.

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