The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Mauro Feliziani - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Shielding design of wireless power transfer systems
2015 31st International Review of Progress in Applied Computational Electromagnetics (ACES), 2015Co-Authors: Tommaso Campi, Silvano Cruciani, Francesca Maradei, Mauro FelizianiAbstract:This paper deals with the Magnetic Shielding design of a wireless power transfer (WPT) system at the frequency of 20 kHz. A numerical investigation is proposed in order to find the best Shielding configuration without degrading the WPT performances.
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Magnetic Shielding of wireless power transfer systems
2014 International Symposium on Electromagnetic Compatibility Tokyo, 2014Co-Authors: Tommaso Campi, Silvano Cruciani, Mauro FelizianiAbstract:This paper deals with the Magnetic Shielding of the field generated by a wireless power transfer (WPT) system at the frequency of 20 kHz. Different Shielding techniques are examined and discussed based on the use of conductive and Magnetic material panels. The performances of the WPT system and the Magnetic field Shielding effectiveness (SE) in presence and in absence of shield panels are calculated and measured.
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Magnetic Shielding of Apertures Loaded by Resistive Coating
IEEE Transactions on Magnetics, 2010Co-Authors: Marcello D'amore, Valerio De Santis, Mauro FelizianiAbstract:The paper deals with the numerical prediction of the Magnetic Shielding of a coated aperture in a perfectly conductive planar shield. The single layer or multilayer thin film resistive coating is characterized and homogenized by using the transmission line approach. The electroMagnetic analysis is performed by two methods: 1) a lumped circuit approach with numerically calculated parameters; 2) a finite element method (FEM) approach using the impedance network boundary conditions (INBCs). The results obtained by the two methods in some test configurations are validated and discussed.
M. Itoh - One of the best experts on this subject based on the ideXlab platform.
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RF Magnetic Shielding Effects of a Compound Plate
2020Co-Authors: Ferrite Plates, Tokoh Nishikubo, Hiroshi Norikane, S. Gokyu, K. Itoh, M. ItohAbstract:With rapid development in the field of information technology, there has been increased interest for electromag- netic Shielding in the radio frequency (RF) region. An excellent RF Magnetic Shielding material can be realized by the use of bincho-charcoal, a high quality charcoal found in Japan, due to its very large value of relative permittivity in the RF region. The present paper has improved the RF Magnetic Shielding character- istics of a bincho-charcoal plate to realize a broadband frequency by the superposition of a ferrite plate over the bincho-charcoal plate. This configuration is termed the compound plate. The RF Magnetic Shielding effects of the compound plate have been examined, including the characteristics of the RF Magnetic effect against both the frequency and the RF Magnetic power. In addi- tion, RF electric Shielding effects have been examined as functions of the frequency and the RF electric power.
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Orientation Characteristics in RF Magnetic Shielding Effects of BPSCCO Plates
IEEE Transactions on Applied Superconductivity, 2009Co-Authors: Tokoh Nishikubo, Hiroki Endo, M. ItohAbstract:As one of the basic areas of research for improvement of the electroMagnetic environment by use of a bulk high-critical temperature superconductor, the present paper has examined a Bi-Pb-Sr-Ca-Cu-O (BPSCCO) plate with a slit, which displays orientation characteristics in the RF Magnetic Shielding. According to the results, the value of the RF Magnetic Shielding degree SD HP, when orienting the slit of the BPSCCO plate perpendicular to the ground, increased in the frequency region of 1 MHz (20 dB) to 30 MHz (40 dB) , and then reminded approximately constant in the region of 30 MHz to 3 GHz (40 dB). The value of the RF Magnetic Shielding degree SD HH when orienting the slit horizontally indicated an average value of 15 dB in the region of 1 MHz to 3 GHz. Namely, the difference in the RF Magnetic Shielding degree, SD HP-SD HH, as related to the direction of the slit represents orientation characteristics. Experimental results revealed several characteristics of the slit BPSCCO plate that include the dependencies of the orientation characteristics on the slit length, slit width, and slit number.
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RF Magnetic Shielding Effects of a Compound Plate Constructed From Bincho-Charcoal and Ferrite Plates
IEEE Transactions on Applied Superconductivity, 2006Co-Authors: Hiroshi Norikane, Tokoh Nishikubo, S. Gokyu, K. Itoh, M. ItohAbstract:With rapid development in the field of information technology, there has been increased interest for electroMagnetic Shielding in the radio frequency (RF) region. An excellent RF Magnetic Shielding material can be realized by the use of bincho-charcoal, a high quality charcoal found in Japan, due to its very large value of relative permittivity in the RF region. The present paper has improved the RF Magnetic Shielding characteristics of a bincho-charcoal plate to realize a broadband frequency by the superposition of a ferrite plate over the bincho-charcoal plate. This configuration is termed the compound plate. The RF Magnetic Shielding effects of the compound plate have been examined, including the characteristics of the RF Magnetic effect against both the frequency and the RF Magnetic power. In addition, RF electric Shielding effects have been examined as functions of the frequency and the RF electric power
Ira Katz - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Shielding of hall thrusters at high discharge voltages
Journal of Applied Physics, 2014Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300–700 V (Isp ≈ 2000–2700 s) at 6 kW, and 800 V (Isp ≈ 3000) at 9 kW. At 6 kW, the Magnetic field topology with which highly effective Magnetic Shielding was previously demonstrated at 300 V has been retained for all other discharge voltages; only the magnitude of the field has been changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. This is because the channel is long enough to allow hot electrons near the channel exit to cool significantly upon reaching the anode. Thus, despite the rise of the maximum electron temperature in the channel with discharge voltage, the electrons along the grazing lines of force remain cold enough to eliminate or reduce significantly parallel gradients of the plasma potential near the walls. Computed ma...
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Magnetic Shielding of a laboratory hall thruster ii experiments
Journal of Applied Physics, 2014Co-Authors: Richard R. Hofer, Ioannis G. Mikellides, Dan M Goebel, Ira KatzAbstract:The physics of Magnetic Shielding in Hall thrusters were validated through laboratory experiments demonstrating essentially erosionless, high-performance operation. The Magnetic field near the walls of a laboratory Hall thruster was modified to effectively eliminate wall erosion while maintaining the Magnetic field topology away from the walls necessary to retain efficient operation. Plasma measurements at the walls validate our understanding of Magnetic Shielding as derived from the theory. The plasma potential was maintained very near the anode potential, the electron temperature was reduced by a factor of two to three, and the ion current density was reduced by at least a factor of two. Measurements of the carbon backsputter rate, wall geometry, and direct measurement of plasma properties at the wall indicate that the wall erosion rate was reduced by a factor of 1000 relative to the unshielded thruster. These changes effectively eliminate wall erosion as a life limitation in Hall thrusters, enabling a new class of deep-space missions that could not previously be attempted.
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The Effectiveness of Magnetic Shielding in High-Isp Hall Thrusters
49th AIAA ASME SAE ASEE Joint Propulsion Conference, 2013Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300-700 V (Isp 2000-2700 s) at 6 kW, and 800 V (Isp 3000) at 9 kW. In this paper we report on the simulation results and their validation with experimental measurements. At 6 kW the Magnetic field topology with which we recently demonstrated highly effective Magnetic Shielding at 300 V was retained for all other discharge voltages; only the magnitude of the field was changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. Maximum erosion rates that remain fairly constant across the range of 300-700 V are computed, with values not exceeding 10-2 mm/kh. Such rates are ~3 orders of magnitude less than those observed in the unshielded version of the same thruster at 300 V. At 9 kW and 800 V, saturation of the Magnetic circuit did not permit us to attain precisely the same Magnetic Shielding topology as that employed during the 6-kW operation since this thruster was not designed to operate at this condition. Consequently, the maximum erosion rate at the inner wall is found to be ~1 order of magnitude higher (~10-1 mm/kh) than that at the 6-kW level. At the outer wall the ion energy is below the sputtering yield threshold so no measurable erosion is expected. The reasons behind the effectiveness of Magnetic Shielding at higher discharge voltages are discussed.
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Channel Wall Plasma Thermal Loads in Hall Thrusters with Magnetic Shielding
47th AIAA ASME SAE ASEE Joint Propulsion Conference & Exhibit, 2011Co-Authors: Ira Katz, Ioannis G. Mikellides, Richard R. HoferAbstract:Computer simulations using Hall2De identified the fundamental physical processes through which Magnetic Shielding can reduce channel wall erosion by orders of magnitude in Hall thrusters. Because Magnetic Shielding reduces significantly the energy and flux of the incident plasma a natural question is whether it has also a large effect on Hall thruster thermal design. In particular, if a Hall thruster is designed with Magnetic Shielding, will it be able to operate at significantly higher power densities than a conventional Hall thruster due to reduced thermal loads to the walls? If Magnetically shielded Hall thrusters can operate at higher power densities, then high power Hall thrusters could be made smaller and lighter than present designs. In this paper we use Hall2De simulations of a laboratory thruster with and without Magnetic Shielding to predict the thermal loads from both ions and electrons including the self-consistently calculated wall sheaths. The formulations are similar to those previously applied in a hollow cathode thermal model. The numerical simulations show that, while Magnetic Shielding reduces high energy ion bombardment and power deposition in the acceleration zone of the discharge chamber, it has little effect on the total plasma thermal loads to thruster surfaces subject to plasma heating. Higher power densities were calculated on thruster surfaces downstream of the discharge chamber for the Magnetic Shielding configuration. Still, the reduction in peak plasma heating in the acceleration zone for the Magnetic Shielding configurations should reduce wall temperatures in this region that may lead to higher power density operation if the power deposition on the downstream surfaces for the Magnetic shielded configuration can be mitigated.
Richard R. Hofer - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Shielding of hall thrusters at high discharge voltages
Journal of Applied Physics, 2014Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300–700 V (Isp ≈ 2000–2700 s) at 6 kW, and 800 V (Isp ≈ 3000) at 9 kW. At 6 kW, the Magnetic field topology with which highly effective Magnetic Shielding was previously demonstrated at 300 V has been retained for all other discharge voltages; only the magnitude of the field has been changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. This is because the channel is long enough to allow hot electrons near the channel exit to cool significantly upon reaching the anode. Thus, despite the rise of the maximum electron temperature in the channel with discharge voltage, the electrons along the grazing lines of force remain cold enough to eliminate or reduce significantly parallel gradients of the plasma potential near the walls. Computed ma...
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Magnetic Shielding of a laboratory hall thruster ii experiments
Journal of Applied Physics, 2014Co-Authors: Richard R. Hofer, Ioannis G. Mikellides, Dan M Goebel, Ira KatzAbstract:The physics of Magnetic Shielding in Hall thrusters were validated through laboratory experiments demonstrating essentially erosionless, high-performance operation. The Magnetic field near the walls of a laboratory Hall thruster was modified to effectively eliminate wall erosion while maintaining the Magnetic field topology away from the walls necessary to retain efficient operation. Plasma measurements at the walls validate our understanding of Magnetic Shielding as derived from the theory. The plasma potential was maintained very near the anode potential, the electron temperature was reduced by a factor of two to three, and the ion current density was reduced by at least a factor of two. Measurements of the carbon backsputter rate, wall geometry, and direct measurement of plasma properties at the wall indicate that the wall erosion rate was reduced by a factor of 1000 relative to the unshielded thruster. These changes effectively eliminate wall erosion as a life limitation in Hall thrusters, enabling a new class of deep-space missions that could not previously be attempted.
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The Effectiveness of Magnetic Shielding in High-Isp Hall Thrusters
49th AIAA ASME SAE ASEE Joint Propulsion Conference, 2013Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300-700 V (Isp 2000-2700 s) at 6 kW, and 800 V (Isp 3000) at 9 kW. In this paper we report on the simulation results and their validation with experimental measurements. At 6 kW the Magnetic field topology with which we recently demonstrated highly effective Magnetic Shielding at 300 V was retained for all other discharge voltages; only the magnitude of the field was changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. Maximum erosion rates that remain fairly constant across the range of 300-700 V are computed, with values not exceeding 10-2 mm/kh. Such rates are ~3 orders of magnitude less than those observed in the unshielded version of the same thruster at 300 V. At 9 kW and 800 V, saturation of the Magnetic circuit did not permit us to attain precisely the same Magnetic Shielding topology as that employed during the 6-kW operation since this thruster was not designed to operate at this condition. Consequently, the maximum erosion rate at the inner wall is found to be ~1 order of magnitude higher (~10-1 mm/kh) than that at the 6-kW level. At the outer wall the ion energy is below the sputtering yield threshold so no measurable erosion is expected. The reasons behind the effectiveness of Magnetic Shielding at higher discharge voltages are discussed.
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Channel Wall Plasma Thermal Loads in Hall Thrusters with Magnetic Shielding
47th AIAA ASME SAE ASEE Joint Propulsion Conference & Exhibit, 2011Co-Authors: Ira Katz, Ioannis G. Mikellides, Richard R. HoferAbstract:Computer simulations using Hall2De identified the fundamental physical processes through which Magnetic Shielding can reduce channel wall erosion by orders of magnitude in Hall thrusters. Because Magnetic Shielding reduces significantly the energy and flux of the incident plasma a natural question is whether it has also a large effect on Hall thruster thermal design. In particular, if a Hall thruster is designed with Magnetic Shielding, will it be able to operate at significantly higher power densities than a conventional Hall thruster due to reduced thermal loads to the walls? If Magnetically shielded Hall thrusters can operate at higher power densities, then high power Hall thrusters could be made smaller and lighter than present designs. In this paper we use Hall2De simulations of a laboratory thruster with and without Magnetic Shielding to predict the thermal loads from both ions and electrons including the self-consistently calculated wall sheaths. The formulations are similar to those previously applied in a hollow cathode thermal model. The numerical simulations show that, while Magnetic Shielding reduces high energy ion bombardment and power deposition in the acceleration zone of the discharge chamber, it has little effect on the total plasma thermal loads to thruster surfaces subject to plasma heating. Higher power densities were calculated on thruster surfaces downstream of the discharge chamber for the Magnetic Shielding configuration. Still, the reduction in peak plasma heating in the acceleration zone for the Magnetic Shielding configurations should reduce wall temperatures in this region that may lead to higher power density operation if the power deposition on the downstream surfaces for the Magnetic shielded configuration can be mitigated.
Dan M Goebel - One of the best experts on this subject based on the ideXlab platform.
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Magnetic Shielding of hall thrusters at high discharge voltages
Journal of Applied Physics, 2014Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300–700 V (Isp ≈ 2000–2700 s) at 6 kW, and 800 V (Isp ≈ 3000) at 9 kW. At 6 kW, the Magnetic field topology with which highly effective Magnetic Shielding was previously demonstrated at 300 V has been retained for all other discharge voltages; only the magnitude of the field has been changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. This is because the channel is long enough to allow hot electrons near the channel exit to cool significantly upon reaching the anode. Thus, despite the rise of the maximum electron temperature in the channel with discharge voltage, the electrons along the grazing lines of force remain cold enough to eliminate or reduce significantly parallel gradients of the plasma potential near the walls. Computed ma...
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Magnetic Shielding of a laboratory hall thruster ii experiments
Journal of Applied Physics, 2014Co-Authors: Richard R. Hofer, Ioannis G. Mikellides, Dan M Goebel, Ira KatzAbstract:The physics of Magnetic Shielding in Hall thrusters were validated through laboratory experiments demonstrating essentially erosionless, high-performance operation. The Magnetic field near the walls of a laboratory Hall thruster was modified to effectively eliminate wall erosion while maintaining the Magnetic field topology away from the walls necessary to retain efficient operation. Plasma measurements at the walls validate our understanding of Magnetic Shielding as derived from the theory. The plasma potential was maintained very near the anode potential, the electron temperature was reduced by a factor of two to three, and the ion current density was reduced by at least a factor of two. Measurements of the carbon backsputter rate, wall geometry, and direct measurement of plasma properties at the wall indicate that the wall erosion rate was reduced by a factor of 1000 relative to the unshielded thruster. These changes effectively eliminate wall erosion as a life limitation in Hall thrusters, enabling a new class of deep-space missions that could not previously be attempted.
-
The Effectiveness of Magnetic Shielding in High-Isp Hall Thrusters
49th AIAA ASME SAE ASEE Joint Propulsion Conference, 2013Co-Authors: Ioannis G. Mikellides, Ira Katz, Richard R. Hofer, Dan M GoebelAbstract:A series of numerical simulations and experiments have been performed to assess the effectiveness of Magnetic Shielding in a Hall thruster operating in the discharge voltage range of 300-700 V (Isp 2000-2700 s) at 6 kW, and 800 V (Isp 3000) at 9 kW. In this paper we report on the simulation results and their validation with experimental measurements. At 6 kW the Magnetic field topology with which we recently demonstrated highly effective Magnetic Shielding at 300 V was retained for all other discharge voltages; only the magnitude of the field was changed to achieve optimum thruster performance. It is found that Magnetic Shielding remains highly effective for all discharge voltages studied. Maximum erosion rates that remain fairly constant across the range of 300-700 V are computed, with values not exceeding 10-2 mm/kh. Such rates are ~3 orders of magnitude less than those observed in the unshielded version of the same thruster at 300 V. At 9 kW and 800 V, saturation of the Magnetic circuit did not permit us to attain precisely the same Magnetic Shielding topology as that employed during the 6-kW operation since this thruster was not designed to operate at this condition. Consequently, the maximum erosion rate at the inner wall is found to be ~1 order of magnitude higher (~10-1 mm/kh) than that at the 6-kW level. At the outer wall the ion energy is below the sputtering yield threshold so no measurable erosion is expected. The reasons behind the effectiveness of Magnetic Shielding at higher discharge voltages are discussed.
