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Magnets for Beam Control and Manipulation
Published in Rob Appleby, Graeme Burt, James Clarke, Hywel Owen, The Science and Technology of Particle Accelerators, 2020
Rob Appleby, Graeme Burt, James Clarke, Hywel Owen
Eddy currents are loops of electrical current induced in a conductor by a changing magnetic field. The name comes from the analogy to water forming eddies or whirlpools in areas of turbulence. The induced current is due to Faraday's Law which states that the voltage, V, induced in a loop of conductor in a region of varying magnetic field is given directly by the rate of change of the magnetic flux, Φ, as V=−dΦdt.
Eddy Currents
Published in Ahmad Shahid Khan, Saurabh Kumar Mukerji, Electromagnetic Fields, 2020
Ahmad Shahid Khan, Saurabh Kumar Mukerji
Eddy currents are circular electric currents induced within conductors by a changing magnetic field in the conductor, in accordance with Faraday’s law of induction. These are also referred to as Foucault currents. These flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an electromagnet or transformer, for example, by relative motion between a magnet and a nearby conductor. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material.
Fields that vary with time
Published in Andrew Norton, Dynamic Fields and Waves, 2019
The most common way of reducing eddy currents is to use a laminated iron block, as shown in Figure 1.30, rather than a solid block. The block is sliced into thin sheets as shown and the sheets are electrically insulated from each other by a thin coat of varnish or shellac, or even by an oxide coating on the surfaces.
Speed-based multiobjective optimisation of a cage-secondary permanent magnet linear eddy current brake
Published in International Journal of Systems Science, 2023
Wen Chen, Baoquan Kou, Mengyao Wang, Xv Niu
Eddy Current Brake is a braking equipment that utilises eddy current effect, which can convert the kinetic energy of the braking unit to the eddy currents in the conductor plate to achieve the purpose of braking. Unlike the conventional adhesion braking, the eddy current is non-contact braking. Therefore, the eddy current brake has the advantages of high reliability, low noise and long service life. With those features, the eddy current brake is considered as a suitable braking device for the braking of transmission system, the rail transit system and so on Gulec et al. (2019), J. Tian et al. (2020), Lubin and Rezzoug (2015), Jin et al. (2022), Mohammadi et al. (2014), Gulec et al. (2021) and Kou et al. (2014). The background of this research is high-speed rail transit braking. In order to increase the reliability of the braking system and avoid the risk of power failure, permanent magnets (PMs) are mostly used in the primary of high-speed braking (Shin et al., 2018). Moreover, as linear high-speed braking requires the long track, it will increase the cost of the manufacture. Therefore, increasing the braking force in all speed ranges to shorten the braking distance and reduce the manufacturing cost are the critical studies of the high-speed rail transit braking system.
Design and actual performance of J-PARC 3 GeV rapid cycling synchrotron for high-intensity operation
Published in Journal of Nuclear Science and Technology, 2022
Kazami Yamamoto, Michikazu Kinsho, Naoki Hayashi, Pranab Kumar Saha, Fumihiko Tamura, Masanobu Yamamoto, Norio Tani, Tomohiro Takayanagi, Junichiro Kamiya, Yoshihiro Shobuda, Masahiro Yoshimoto, Hiroyuki Harada, Hiroki Takahashi, Yasuhiro Watanabe, Kota Okabe, Masahiro Nomura, Taihei Shimada, Takamitsu Nakanoya, Ayato Ono, Katsuhiro Moriya, Yoshio Yamazaki, Kazuaki Suganuma, Kosuke Fujirai, Nobuhiro Kikuzawa, Shin-Ichiro Meigo, Motoki Ooi, Shuichiro Hatakeyama, Tomohito Togashi, Kaoru Wada, Hideaki Hotchi, Masahito Yoshii, Chihiro Ohmori, Takeshi Toyama, Kenichirou Satou, Yoshiro Irie, Tomoaki Ueno, Koki Horino, Toru Yanagibashi, Riuji Saeki, Atsushi Sato, Osamu Takeda, Masato Kawase, Takahiro Suzuki, Kazuhiko Watanabe, Tatsuya Ishiyama, Shinpei Fukuta, Yuki Sawabe, Yuichi Ito, Yuko Kato, Kazuo Hasegawa, Hiromitsu Suzuki, Fumiaki Noda
Figure 10 shows the typical vacuum pressure distribution in the RCS. There are unique requirements to ensure stable vacuum conditions in the RCS [38]. The first requirement is the suppression of the eddy current in the vacuum duct inside the magnet. The main magnets, such as the dipole and quadrupole magnets, are excited by the sinusoidal current at 25 Hz. Moreover, the injection pulse magnets operate at a repetition rate of 25 Hz and their excitation pulse structures comprise high-frequency components. The presence of an electric conductor, such as a metal, in a time-varying magnetic field produces eddy currents, which result in induced magnetic fields and heat generation. To avoid this effect, we have developed certain ceramic vacuum chambers to be placed in these magnets [39–41]. However, if the vacuum chambers over the entire circumference are completely insulated with the ceramic material, a wall current would not be able to move with the beam, and the impedance of the beamline would increase [42,43]. Therefore, the ceramic chamber has an RF shield [44] to conduct the wall current; its width had been defined as per the chamber’s ability to sufficiently suppress the eddy current [45]. The interior of the ceramic chamber is covered with titanium nitride films to reduce vapor absorption in air and secondary electron emission. Figure 11 shows the image of the ceramic chamber.
Pull-off strength of fiber-reinforced composite polymer coatings on aluminum substrate
Published in The Journal of Adhesion, 2021
Paulina Mayer, Anna Dmitruk, Marta Jóskiewicz, Mateusz Głuch
After complete curing of the produced coatings, measurements of coating thickness were conducted. For this purpose, a coating thickness gauge MiniTest 730/Sensor FN 5 by ElektroPhysik was used. This device allows to measure the thickness of coatings on both ferromagnetic and non-magnetic metals. The measurements were carried out in accordance with the PN-EN ISO 2808: 2008 standard.[42] One of the major non-destructive testing methods, the eddy current method, was used to measure the thickness of coatings on an aluminum substrate. Eddy currents are induced in electrically conductive materials due to the action of an alternating magnetic field. They form closed circuits inside the conductor, and the resulting magnetic field as a result of the eddy current flow affects the field of the coil according to Lenz’s law. Measurements were carried out using a special electromagnetic probe.