Attenuation of secondary electron emission from divertor plates due to magnetic field inclination

AbstractThe secondary electron emission process is essential for the optimal operation of a wide range of applications, including fusion reactors, high-energy accelerators, or spacecraft. The process can be influenced and controlled by the use of a magnetic field. An analytical solution is proposed to describe the secondary electron emission process in an oblique magnetic field. It was derived from Monte Carlo simulations. The analytical formula captures the influence of the magnetic field magnitude and tilt, electron emission energy, electron reflection on the surface, and electric field intensity on the secondary emission process. The last two parameters increase the effective emission while the others act the opposite. The electric field effect is equivalent to a reduction of the magnetic field tilt. A very good agreement is shown between the analytical and numerical results for a wide range of parameters. The analytical solution is a convenient tool for the theoretical study and design of magnetically assisted applications, providing realistic input for subsequent simulations.

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Secondary electron emission from solid surface in an oblique magnetic field

Journal of Nuclear Materials ◽

10.1016/0022-3115(94)00509-5 ◽

1995 ◽

Vol 220-222 ◽

pp. 488-492 ◽

Cited By ~ 21

Author(s):

S. Mizoshita ◽

K. Shiraishi ◽

N. Ohno ◽

S. Takamura

Keyword(s):

Magnetic Field ◽

Solid Surface ◽

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Oblique Magnetic Field

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Magnetic Field Effects on Secondary Electron Emission in Hall Thrusters

44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit ◽

10.2514/6.2008-4725 ◽

2008 ◽

Author(s):

Robert Santos ◽

Eduardo Ahedo

Keyword(s):

Magnetic Field ◽

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission ◽

Hall Thrusters ◽

Magnetic Field Effects ◽

Field Effects

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Suppression of secondary electron emission in a magnetic field

Soviet Physics Journal ◽

10.1007/bf00895202 ◽

1984 ◽

Vol 27 (12) ◽

pp. 1017-1021

Author(s):

V. I. Volosov ◽

I. N. Meshkov ◽

A. V. Shemyakin

Keyword(s):

Magnetic Field ◽

Electron Emission ◽

Secondary Electron ◽

Secondary Electron Emission

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The System for Control and Stabilization of the Beam Position in the Microtron MT-25 in Prague

Acta Polytechnica ◽

10.14311/520 ◽

2004 ◽

Vol 44 (1) ◽

Author(s):

Č. Šimáně ◽

M. Vognar ◽

D. Chvátil

Keyword(s):

Magnetic Field ◽

Electron Emission ◽

Secondary Electron ◽

Beam Quality ◽

Secondary Electron Emission ◽

Remote Measurement ◽

Output Window ◽

Beam Position ◽

Wire Probe ◽

The Wire

A method of control the beam position at crucial points of the transport system and for the stabilization of its output position has been proposed and preliminary tested. The method is based on secondary electron emission from a thin metallic wire probe induced by electrons from the 25 MeV microtron. It was demonstrated, that magnetic field of the order of 0.2 T and parallel to the wire probe in front of the orifice of the extraction channel in the acceleration space, does not prevent the functioning of the method. A strong parasitic effect of secondary electron emission from the material of the channel and its support construction was found, leading to the inversion of the electron current polarity from the wire. This effect can be to great extent eliminated by negative electric potential bias relative to the channel. At the electron output current of 1 mA the secondary emission current from the wire probe of 0.3 mm diameter is of the order of several nA. Two electromechanical systems were designed for the removal of the probes from the beam path, to avoid the deterioration of the electron beam quality by scattering. Electronic schemes used for remote measurement of small probe currents, suppressing the influence of strong electromagnetic noise, are described. For stabilization of the output beam position two wire probes situated in air close to the Al output window were used. These probes having been placed at the periphery of the beam did not deteriorate the beam quality. The difference of their emission currents was used as an error signal to control the magnetic field of the last dipole, which kept the beam in the center of the output window.

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