scholarly journals Низкоэнергетическое состояние электронного пучка в коаксиальном диоде с однородным анодом и неоднородным профилем магнитного поля

Author(s):  
А.В. Громов ◽  
М.Б. Гойхман ◽  
Н.Ф. Ковалев ◽  
А.В. Палицин ◽  
M.I. Fuks ◽  
...  

AbstractThe possible formation of an extended low-energy state of electron beam in a coaxial diode with homogeneous cylindrical anode and moderate magnetic field with inhomogeneous profile is demonstrated for the first time. It is established that, depending on the magnetic field configuration, virtual cathodes (VCs) of two types can be formed: (i) a stationary VC with a localized reflection plane and (ii) a moving VC with a two-stream low-energy state of the electron beam.

Plasma ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 222-228 ◽  
Author(s):  
Mikhail Fuks ◽  
Dmitrii Andreev ◽  
Artem Kuskov ◽  
Edl Schamiloglu

In our earlier work, we showed that a low-energy state of an electron beam exists in a nonuniform channel between two virtual cathodes in a magnetron with diffraction output, which consists of three uniform sections with increasing radius. A uniform axial magnetic field fills the interaction space. This led to magnetron operation with >90% efficiency when combined with a magnetic mirror field at the output end. In this present paper, we show that a low-energy state of an electron beam can be realized in a uniform channel in which an increasing magnetic field is used in order to create a magnetic mirror at the output end. We consider two cases, one where the injected beam current slightly exceeds the space-charge-limiting current and the other where the injected beam current greatly exceeds the space-charge-limiting current. On the time scale of relevance to planned experiments (∼30 ns), when the injected current slightly exceeds the space-charge-limiting current a stationary virtual cathode forms and when the injected current greatly exceeds the space-charge-limiting current the virtual cathode oscillates back and forth.


2018 ◽  
Vol 44 (10) ◽  
pp. 949-952 ◽  
Author(s):  
A. V. Gromov ◽  
M. B. Goykhman ◽  
N. F. Kovalev ◽  
A. V. Palitsin ◽  
M. I. Fuks ◽  
...  

Author(s):  
D. E. Speliotis

The interaction of electron beams with a large variety of materials for information storage has been the subject of numerous proposals and studies in the recent literature. The materials range from photographic to thermoplastic and magnetic, and the interactions with the electron beam for writing and reading the information utilize the energy, or the current, or even the magnetic field associated with the electron beam.


2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.


2020 ◽  
Author(s):  
Ovidiu Dragoş Constantinescu ◽  
Hans-Ulrich Auster ◽  
Magda Delva ◽  
Olaf Hillenmaier ◽  
Werner Magnes ◽  
...  

Abstract. In situ measurement of the magnetic field using space borne instruments requires either a magnetically clean platform and/or a very long boom for accommodating magnetometer sensors at a large distance from the spacecraft body. This significantly drives up the costs and time required to build a spacecraft. Here we present an alternative sensor configuration and an algorithm allowing for ulterior removal of the spacecraft generated disturbances from the magnetic field measurements, thus lessening the need for a magnetic cleanliness program and allowing for shorter boom length. The proposed algorithm is applied to the Service Oriented Spacecraft Magnetometer (SOSMAG) onboard the Korean geostationary satellite GeoKompsat-2A (GK2A) which uses for the first time a multi-sensor configuration for onboard data cleaning. The successful elimination of disturbances originating from several sources validates the proposed cleaning technique.


2014 ◽  
Vol 9 (S307) ◽  
pp. 389-390
Author(s):  
Coralie Neiner ◽  

AbstractUVMag is a medium-size space telescope equipped with a high-resolution spectropolarimetrer working in the UV and visible domains. It will be proposed to ESA for a future M mission. It will allow scientists to study all types of stars as well as e.g. exoplanets and the interstellar medium. It will be particularly useful for massive stars, since their spectral energy distribution peaks in the UV. UVMag will allow us to study massive stars and their circumstellar environment (in particular the stellar wind) spectroscopically in great details. Moreover, with UVMag's polarimetric capabilities we will be able, for the first time, to measure the magnetic field of massive stars simultaneously at the stellar surface and in the wind lines, i.e. to completely map their magnetosphere.


2021 ◽  
Author(s):  
Sae Aizawa ◽  
Nicolas André ◽  
Ronan Modolo ◽  
Elisabeth Werner ◽  
Jim Slavin ◽  
...  

&lt;p&gt;&lt;span lang=&quot;EN-GB&quot;&gt;BepiColombo is going to conduct its first Mercury flyby in October 2021. During this flyby,&amp;#160; plasma measurement will be obtained and bring new insights on the Hermean magnetosphere and its interaction with the Sun despite the limited field of view of the instruments during the cruise phase. Unlike Mariner-10 ion measurements will be obtained, and unlike MESSENGER, low energy electrons and ions will be measured simultaneously. In this study, we have revisited Mariner 10 and MESSENGER observations with the help of the global hybrid model LatHyS in order to understand the influence of time-variable solar wind and to constraint the plasma environment. We are able to reproduce the magnetic field observations of Mariner 10 along its trajectory with in particular two distinct signatures consisting of a quiet and disturbed state of the magnetosphere. In addition, the plasma spectrogram is also collected in the model and this enables us to detail the properties of the charged particles observed during the flyby. We will discuss all these signatures both in term of an interaction with a time-variable solar wind and localized processes occurring in the magnetosphere. We will then present the virtual sampling of both the magnetic field and plasma spectrogram along BepiColombo&amp;#8217;s first Mercury flyby trajectory and discuss the possible signatures to be observed at that time.&lt;/span&gt;&lt;/p&gt;


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