Electromagnetic Probe Research Articles

Current status of tokamak T-15MD

Abstract At the present time, the preparation to physical start-up of tokamak T-15MD is completed in the National Research Center “Kurchatov Institute”. The main parameters of T-15MD are: R = 1.48 m, a = 0.67 m, B = 2.0 T, Ipl = 2.0 MA. The magnet system is capable to maintain without overheating (more 60 °C) the plasma current of 2 MA for 4 s, 1 MA for 20 s, 700 kA for 40 s, 500 kA for 80 s, 300 kA for 160 s and 250 kA for 400 s. Plasma current drive can be maintained either by injection of fast neutrals or by electron cyclotron (EC)-, ion cyclotron (IC)- and low hybrid (LH) - waves. In August 2019 the electromagnetic system, consisting of TF and PF coils, together with vacuum vessel have been assembled in experimental hall. Power supply system of Tokamak T-15MD includes: two substations 110/10 kV, two substations 10/0.83 kV, thyristor convertors and different equipment. Total power consumption during the pulse with plasma current 2 MA and additional plasma heating of 20 MW will consist of 300 MVA. Power supply system is in the commissioning. Tokamak T-15MD will be operate using the information and control system. All the information and control system equipment, required for the implementation of physical start-up of tokamak T-15MD, is available. For plasma control the 250 different electromagnetic probes are installed inside vacuum vessel. The gyrotron with frequency 82.6 GHz and power of 1 MW will be used for pre-ionization.

Design/exploration and verification of an electromagnetic probe for assessing dental implant osseointegration

Osseointegration is the key to the success of surgery of dental implantation. In this study, we proposed, implemented and explored a handheld and noncontact electromagnetic-type stability assessment device for the use after surgery. The device with two pairs of dual inductors incorporating with a driving signal of swept wavelets was first proposed. This detection device feeds 200–10 kHz of alternating current into an inductor to produce swept broadband magnetic flux and excite the implant structure with a magnetic pole. The implant vibration causes magnetic-flux changes and generates an induced electromotive force. The implant structure resonance frequency (RF) can be characterized to exhibit osseointegration status by evaluating the frequency response function. In vitro bone block experiment and in vivo animal testing were performed to validate the developed device. For bone block experiment on fourteen designs, besides two cancellous bones and two cortical-shell thicknesses, four interface tissues produced using varied mixing ratios of epoxy adhesive were to imitate osseointegration progress. Further, a pilot animal test was conducted on five female New Zealand rabbits to assess implant osseointegration in live bodies. Statistical analyses for varied bone models on measured RF, and the regression analysis between the measured RF and OsstellTM ISQ for in vivo testing were performed. The correlation analysis on the built regression models shows a close relationship between the measured RFs and ISQ quotients with the determination coefficients up to over 0.9.

Investigation of DC Electromagnetic-Based Motion Induced Eddy Current on NDT for Crack Detection

Cracks caused by long-term cyclic loading and harsh working environment may seriously lead to the catastrophic industrial safety accidents. Therefore, a quantitative and accurate characterization for the cracks is necessary to ensure safety of the key component (e.g. rolling contact fatigue of high speed rail track in particular). This article investigates the motion induced eddy current (MIEC) of a direct current (DC) electromagnetic nondestructive testing (NDT) and proposes an approach to quantitative characterization the cracks in moving ferromagnetic material. The velocity effect as well as the distribution of MIEC of the ferromagnetic material under the DC electromagnetic probe are investigated firstly. Then, the relationships between the crack depth/width and detection signals are discovered. Finally, a quantitative characterization method of crack depth/width is proposed by experiment. The investigations indicate that for DC electromagnetic NDT, the dragging effect is related to the rate of the MIEC diffusion time, which is inversely proportional to the conductivity and permeability of metal, therefore, the higher speed, the more obvious the dragging effect is. The experiments show that the crack depth/width can be characterized quantitatively by the peak separation and differential value. The investigation in this article show that the DC electromagnetic based on MIEC can be used not only for the crack detection in moving ferromagnetic metals such as bearings, gears, etc., but also for the quantitative characterization of cracks when there is rapid relative motion between the detection devices and the ferromagnetic metals (e.g., rail, pipe, etc.).

Testing the general theory of relativity using gravitational wave propagation from dark standard sirens

ABSTRACT Alternative theories of gravity predict modifications in the propagation of gravitational waves (GW) through space–time. One of the smoking-gun predictions of such theories is the change in the GW luminosity distance to GW sources as a function of redshift relative to the electromagnetic (EM) luminosity distance expected from EM probes. We propose a multimessenger test of the theory of general relativity from the propagation of GWs by combining EM and GW observations to resolve these issues from GW sources without EM counterparts (which are also referred to as dark standard sirens). By using the relation between the geometric distances accessible from baryon acoustic oscillation measurements, and luminosity distance measurements from the GW sources, we can measure any deviation from the general theory of relativity via the GW sources of unknown redshift that will be detectable by networks of GW detectors such as LIGO, Virgo, and KAGRA. Using this technique, the fiducial value of the frictional term can be measured to a precision $\Xi _0=0.98^{+0.04}_{-0.23}$ after marginalizing over redshift dependence, cosmological parameters, and GW bias parameters with ∼3500 dark standard sirens of masses $30\, \rm M_\odot$ each distributed up to redshift z = 0.5. For a fixed redshift dependence, a value of $\Xi _0=0.99^{+0.02}_{-0.02}$ can be measured with a similar number of dark sirens. Application of our methodology to the far more numerous dark standard sirens detectable with next-generation GW detectors, such as LISA, Einstein Telescope and Cosmic Explorer, will allow achievement of higher accuracy than possible from use of bright standard sirens.

The multipolar structure of fuzzballs

We extend and refine a general method to extract the multipole moments of arbitrary stationary spacetimes and apply it to the study of a large family of regular horizonless solutions to mathcal{N} = 2 four-dimensional supergravity coupled to four Abelian gauge fields. These microstate geometries can carry angular momentum and have a much richer multipolar structure than the Kerr black hole. In particular they break the axial and equatorial symmetry, giving rise to a large number of nontrivial multipole moments. After studying some analytical examples, we explore the four-dimensional parameter space of this family with a statistical analysis. We find that microstate mass and spin multipole moments are typically (but not always) larger that those of a Kerr black hole with the same mass and angular momentum. Furthermore, we find numerical evidence that some invariants associated with the (dimensionless) moments of these microstates grow monotonically with the microstate size and display a global minimum at the black-hole limit, obtained when all centers collide. Our analysis is relevant in the context of measurements of the multipole moments of dark compact objects with electromagnetic and gravitational-wave probes, and for observational tests to distinguish fuzzballs from classical black holes.

Near-Field Precision Measurement System of High-Density Integrated Module

An automatic near-field precision measurement system was proposed in this article. The work was mainly focused on the hardware structure design of the near-field precision measurement system and the software development of the upper computer. At the same time, the electromagnetic field probes used in the system were selected and introduced. The near-field precision measurement system was composed of an upper computer control part, motion controller, power amplifier module, three-axes mechanical arms, spectrum analyzer, and near-field probes. Three-axes mechanical arm, multi-degree-of-freedom fixture, and electromagnetic field probe cooperate with each other for near-field measurement. The electromagnetic radiation emission of high-density integrated module and liquid crystal display (LCD)-printed circuit board (PCB) of laptop computer were measured. According to the measured data, the visual field distribution map was generated, and the measured results were analyzed. Compared with manual measurement method and commercial electromagnetic compatibility (EMC) scanners, the near-field precision measurement system has more accurate measurement results and can accurately locate the noise source.

A Novel Probe of DC Electromagnetic NDT Based on Drag Effect: Design and Application in Crack Characterization of High-Speed Moving Ferromagnetic Material

Electromagnetic nondestructive testing (NDT) of high-speed moving ferromagnetic material is a challenging topic; due to the relative motion between ferromagnetic material and detection devices, motion-induced eddy current (MIEC) will be generated and the drag effect will show up, which result in a more complex magnetic field distribution in the ferromagnetic material than static or quasi-static testing. Therefore, an electromagnetic NDT probe, which is suitable for multiple crack detection in high-speed moving ferromagnetic materials, is urgently required. In this article, a novel probe of dc electromagnetic NDT based on drag effect is designed considering the strength and sensitivity of the detection signal by experiment, and then it is applied to crack characterization of high-speed moving ferromagnetic material. After that, the measurement uncertainty of the detection signal based on a multiconvolutional approach is investigated and estimated. The investigation indicated that the proposed probe can quantitatively characterize the multiple cracks at 20 m/s within the relative error and standard deviation of 10% when the crack depth is deeper than 1.0 mm; furthermore, the deeper the crack, the higher the experimental repeatability. Accordingly, the proposed probe can be expected to detect the multiple cracks in high-speed moving ferromagnetic materials, such as rotating bearings, pipelines, and high-speed railway.

Counterfeit IC Detection Research Based on BP-AdaBoost Model and Genetic Algorithm

In view of the increasingly prominent problems exposed by chips in integrated circuits and the destructive problems of traditional chip detection methods, a BPAdaBoost neural network model based on genetic algorithm optimization was proposed and applied to chip detection and classification. By using electromagnetic probes to collect the electromagnetic signals generated by different chips in the same operating state and using the electromagnetic radiation signals as the basis for chip identification and classification, the signals are put into the BP-AdaBoost model optimized by genetic algorithm for learning and training. Experimental results show that this method has good effect in the application of chip recognition and classification.

Electromagnetic and weak probes: theory

An overview of the latest theoretical developments and results on electromagnetic and weak probes in relativistic heavy-ion collisions is presented. The possibilities to use electromagnetic probes, i.e., photons and dileptons, as a spectrometer, thermometer, chronometer, polarimeter, barometer, and multimeter of the collision system, as well as on their application to explore the QCD phase diagram and to locate phase transitions such as the critical endpoint, are discussed.

Electromagnetic & Weak Probes: Experimental Overview

Electromagnetic and electroweak probes are the most versatile probes in the study of heavy-ion collisions. Produced at every stage in the evolution of QCD matter, its messengers are practically inert to the strongly interacting medium they travel through. In this contribution, I will discuss a selection of new results from experiments at the LHC, RHIC, and SIS facilities, spanning almost four orders of magnitude in beam energy. I will conclude with a brief overview of the experimental landscape in the near future.

A model for neutrino-nucleus interactions in the GeV region

We review the recent progress in modelling neutrino-nucleus scattering, in a framework based on scaling which describes simultaneously the nuclear response to electromagnetic and weak probes. The study is relevant for the analysis of neutrino oscillation data and the design of the next generation experiments Hyper-Kamiokande and DUNE.

A Zynq-Based Flexible ADC Architecture Combining Real-Time Data Streaming and Transient Recording

The RFX-mod2 Nuclear Fusion experiment is an upgrade of RFX-mod, which was shutdown in 2016. Among the other improvements in the machine structure and diagnostics, a larger number of electromagnetic probes (EMs) is foreseen to provide more information about plasma instabilities and to allow an improved real-time plasma control. An analog-to-digital converter (ADC) architecture able to provide, at the same time, both transient recording and real-time streaming, as well as field-programmable gate array (FPGA)-based time integration of the inputs, is foreseen in RFX-mod2. Transient recording provides full-speed data acquisition (up to 1 MSample/s) by recording data in local memory and reading memory content after the plasma discharge. Real-time streaming of the subsampled data is required for active control. The chosen technology is based on the XILINX Zynq architecture that provides, in the same chip, a multicore Advanced RISC Machines (ARM) processor tightly coupled to an FPGA. Time-critical functions are carried out by the FPGA, such as the management of the circular data buffer, low-pass filtering for subsampling of the samples to be streamed, and digital integration. Other functions are carried out by the processor, such as the management of the configuration setting, received via Transmission Control Protocol (TCP)/IP or Hypertext Transfer Protocol (HTTP), the data readout of acquired samples in transient recording buffers, and network data streaming of data collected for active real-time plasma control.

Magnetic dipole excitations based on the relativistic nuclear energy density functional

Magnetic dipole (M1) excitations build not only a fundamental mode of nucleonic transitions, but they are also relevant for nuclear astrophysics applications. We have established a theory framework for description of M1 transitions based on the relativistic nuclear energy density functional. For this purpose the relativistic quasiparticle random phase approximation (RQRPA) is established using density dependent point coupling interaction DD-PC1, supplemented with the isovector-pseudovector interaction channel in order to study unnatural parity transitions. The introduced framework has been validated using the M1 sum rule for core-plus-two-nucleon systems, and employed in studies of the spin, orbital, isoscalar and isovector M1 transition strengths, that relate to the electromagnetic probe, in magic nuclei $^{48}$Ca and $^{208}$Pb, and open shell nuclei $^{42}$Ca and $^{50}$Ti. In these systems, the isovector spin-flip M1 transition is dominant, mainly between one or two spin-orbit partner states. It is shown that pairing correlations have a significant impact on the centroid energy and major peak position of the M1 mode. The M1 excitations could provide an additional constraint to improve nuclear energy density functionals in the future studies.

Dielectron simulations for the CBM-TRD

This report features the simulation studies of dielectron decays with the compressed baryonic matter experiment in the regime of high net-baryon densities and moderate temperatures. The corresponding region in the QCD phase-diagram is completely unexplored with leptonic channels and could provide essential insight into potential phase transitions to a QGP-phase or chiral symmetry restoration. At CBM energies there is undisturbed access to the decay channel of prompt thermal photons into dielectron pairs in the intermediate mass range between 1.1 and 2.5 GeV/c. Due to the rare character of such electromagnetic probes, very high statistics and a powerful particle identification are crucial. With the combination of a RICH detector and the TRD, CBM will measure these signals with a sufficient significance, as will be demonstrated in this work.

Theoretical and Methodological Substantiation of Transient Electromagnetic Sounding from the Arctic Drift Ice

Abstract —Marine geoelectromagnetic sounding with artificial sources is strongly hindered by the influence of a conductive seawater layer. There is only one known wide successful application of electrical prospecting in this field – Controlled Source Electromagnetic Method (CSEM). However, this method has unfortunate limitations: the need to submerge an electromagnetic probe to the bottom of a deep (more than 1000 m) sea and the great rafting (~15 km). The method is not applicable in an ice-covered sea. Deep sounding from the sea surface and, hence, from the ice surface is possible if the TM polarization field is used. This field is generated by a vertical electric line (VEL) or a circular electric dipole (CED). The former has drawbacks even when it is used at sea. At the same time, a CED is efficient in one-dimensional and three-dimensional media in frequency and time modes. We have developed a three-dimensional mathematical tool for the CED field in the Born approximation, which is quite adequate in a conductive section with deep local inhomogeneities. The research is carried out within the framework of a geophysical project using the Arctic drift ices.

Inspection Method of Outer Side Defect in Ferromagnetic Steel Tube by Insertion-Type Electromagnetic Sensor Using Square Wave Alternating Magnetic Field With DC Bias

The ferromagnetic steel tubes are used for heat transfer tubes of heat exchangers in power plants or oil plants. The outside defect in the ferromagnetic steel tube is generated by friction with the supporting steel plate (baffle). In this research, in order to detect the outer side defect in the ferromagnetic steel tubes, the electromagnetic inspection sensor probe of the type inserted in the ferromagnetic steel tubes using square wave alternating magnetic field with dc bias is proposed. The flux density and eddy current in the ferromagnetic steel tubes are estimated by the 3-D nonlinear finite-element method (FEM) taking account of minor loop curve using the play hysterons model method. The usefulness of this proposal inspection method is shown also from comparison with an experimental verification.

Strong QCD Insights from Excited Nucleon Structure Studies with CLAS and CLAS12

Studies of the spectrum of hadrons and their structure in experiments with electromagnetic probes offer unique insight into many facets of the strong interaction in the regime of large quark-gluon running coupling, {\it i.e.} the regime of strong QCD. The experimental program within Hall~B at Jefferson Laboratory based on data acquired with the CLAS spectrometer using electron and photon beams with energies up to 6~GeV has already considerably extended the scope of research in hadron physics in joint efforts between experiment and phenomenological data analysis. Impressive progress in relating the hadron structure observables inferred from the data to the strong QCD mechanisms underlying hadron mass generation has been achieved in the past decade. These results will be considerably extended with data from the experimental program with the new CLAS12 spectrometer that has begun data taking using electron beams with energies up to 11~GeV. With this extended kinematic reach the structure of nucleon resonances will be probed at the highest photon virtualities ever achieved in the studies of exclusive electroproduction, which will allow for the exploration of the distance scale where $>$98\% of light hadron mass emerges from QCD in the transition of the strong interaction from the regime of quark-gluon confinement to perturbative QCD.

Evaluation of electrical properties of ex vivo human hepatic tissue with metastatic colorectal cancer

Objective: To probe the distribution of electrical properties in tumor-bearing human hepatic tissues with metastatic colorectal cancer. Approach: Electrochemical impedance spectroscopy (EIS) and a non-contact electromagnetic probe were used for distinguishing spatial heterogeneities in fresh, unfixed human hepatic tissues ex vivo from patients with metastatic colorectal cancer (CRC). Main results: Point-wise EIS measurements reported over a frequency range of 100 Hz–1 MHz showed that the interface tissue between visible tumor and normal tissue exhibits an electrically different domain (p < 0.05) from both normal tissue (over 100 Hz–100 kHz) and tumor tissue (over 100 Hz–1 MHz). Observations of the microstructure on tumor-bearing hepatic tissue from hematoxylin and eosin stained images and the equivalent circuit modelling were used to validate the impedance measurements and characterize previously unidentified interfacial domain between normal and tumor tissue. Lastly, in a proof of concept study, a new in-house designed non-contact electromagnetic probe, as opposed to the invasive EIS measurements, was demonstrated for distinguishing tumor tissue from the normal tissue in a hepatic tissue specimen from a patient with metastatic CRC. Significance: EIS measurements, correlated with histological observations, show potential for mapping electrical properties in tumor-bearing human hepatic tissue.

Cone-Beam CT Image Guidance With and Without Electromagnetic Navigation Bronchoscopy for Biopsy of Peripheral Pulmonary Lesions.

Background:Bronchoscopic diagnosis of small peripheral lung lesions suspected of lung cancer remains a challenge. A successful endobronchial diagnosis comprises navigation, confirmation, and tissue acquisition. In all steps, 3-dimensional information is essential. Cone-beam computed tomography (CBCT) imaging can provide computed tomography information and 3-dimensional augmented fluoroscopy imaging. We assessed whether CBCT imaging can improve navigation and diagnosis of peripheral lesions by 2 clinical workflows with a cross-over design: (1) a primary CBCT and radial endobronchial ultrasound mini probe imaging–based approach and (2) a primary electromagnetic navigation (EMN) and radial endobronchial ultrasound mini probe imaging–based approach.Methods:All patients with a peripheral lung lesion biopsy indication were eligible for study inclusion and randomly assigned to study arms. Commercially available equipment was used. The main study goals were to assess CBCT-confirmed navigation success and diagnostic accuracy. Surgery or unambiguous clinical follow-up served as the gold standard.Results:Eighty-seven patients with 107 lesions were included. Lesion mean longest axis size in the CBCT arm was 16.6 mm (n=47) and 14.2 mm in the EMN arm (n=40). The primary CBCT approach and primary EMN approach had 76.3% and 52.2% navigation success, respectively. Addition of EMN to the CBCT approach increased navigation success to 89.9%. Addition of CBCT imaging to the EMN approach significantly increased navigation success to 87.5% per lesion. The overall diagnostic accuracy per patient was significantly lower than the navigation success, being 72.4%.Conclusion:CBCT imaging is a valuable addition to navigation bronchoscopy. Although overall navigation success was high, the diagnostic accuracy remains to be improved. Future research should focus on improving the tissue acquisition methodology.

Error field feedback control system in the Keda Torus eXperiment and open loop control experiment

A feedback control system has been designed for the Keda Torus eXperiment device to achieve the following goals: (a) suppression of the error field at the poloidal gap, (b) three-dimensional plasma stability control, and (c) improvement of plasma discharge quality. The system consists of a boundary electromagnetic probe array, a field-programmable gate array, a linear power amplifier, and an active control coil array. The system adopts a compound control method that includes both active and passive control methods. To control the plasma, an active control coil array is used to generate a localized radial magnetic field as needed at two poloidal gaps of the device. In the open-loop control experiment, the active control coils near the poloidal gaps reduced the original error field and thus increased the plasma discharge current amplitude by 50% and effectively extended the plasma discharge duration.