Radio Frequency Waves Research Articles

Multiscale Modeling of Radio Frequency Reactor Coupled Catalyst Heating for Ethylene Production

Ethylene is the petrochemical compound with the highest production worldwide. Whether reactors are heated by direct fired heating or indirect heating via steam, manufacturers rely on economies of scale to overcome inherent thermodynamic inefficiencies while burning fossil fuels. New approaches to supply energy to chemical reactor systems can reduce energy waste created by traditional techniques while enabling large scale facilities to use other sources of raw materials and energy. Electromagnetic (EM) induction heating is one potential solution for providing energy efficiently to reactor systems. By taking advantage of the nature of radio frequency (RF) waves, heterogeneous-catalyst can be precisely targeted for heating inside the reactors. Site-selective heating can significantly reduce the energy requirements of the process by providing heat at reaction sites and reducing unnecessary heat transfer elsewhere. Other advantages to an EM enhanced system include rapid volumetric heating, broader turn-down capacity, and reduced process footprint.The purpose of this work is to establish a multiscale computational fluid dynamics (CFD) model that can be used to emulate the proposed process mechanics at the macroscale and microscale. At the macroscale, coil geometry (coil diameter, gap between coils, distance between coil and susceptors) is investigated to elucidate coil design and effects on heating rates. In the microscale, the oxidative (CO2) dehydrogenation (ODH) of ethane is explored using different catalysts and possible catalyst/susceptor configurations with heat supplied by an EM susceptor. This multiscale method can also be applied to electrochemical systems.

Penatalaksanaan Pemeriksaan MRI Cervical Pada Kasus Syringomyelia Pada Medulla Spinalis Di Rumah Sakit Primaya Tangerang

Management of Cervical MRI Examination in Cases of Syringomyelia in the Spinal Medulla at Primaya Hospital Tangerang. Magnetic Resonance Imaging (MRI) is a state-of-the-art diagnostic tool for examining and detecting the body using a large magnetic field and radio frequency waves, without the use of X-rays or radioactive materials, which produces cross-sectional images of the human body/organs using a magnetic field. strength between 0.064 – 1.5 tesla (1 tesla = 1000 Gauss) and vibrational resonance of the hydrogen atom nucleus. MRI can produce images of the vertebral column, spinal cord, and also the CSF. The MRI screening procedure is ideal for the differential diagnosis of structural disorders that can affect the spinal roots and spinal cord. This examination is used in carrying out a vertebral examination at once, namely scanning starting directly from the cervical vertebrae and also up to the sacrum. So this examination can directly diagnose the cervical, thoracic, lumbar, sacral vertebrae and also includes the coccyx. The purpose of this study was to determine the management of cervical MRI examination with clinical syringomyelia. This research is descriptive qualitative with a case study approach. The subject is a patient with clinical syringomyelia. All subjects underwent Cervical MRI examination at 1.5 tesla to find out the sequence and procedure and sequence information used. From the research results obtained according to the theory using T1-weighted imaging with administration of contrast agent. While in the field using the cervical MRI protocol without contrast, it is sufficient to establish a diagnosis using an examination procedure with a localizer sequence design, sagittal T1, Axial T1 FSE, Axial T2, Axial 2D marge, sagittal T2 fat sat, Axial T2 thoracic 2-3, myelo 2D. The T2 fat sat sagittal sequence section makes it possible to see the anatomy, namely syringomyelia.

A D‐Region Ionospheric Imaging Method Using Sferic‐Based Tomography

AbstractWe present a tomographic imaging technique for the D‐region electron density using a set of spatially distributed very low frequency (VLF) remote sensing measurements. The D‐region ionosphere plays a critical role in many long‐range and over‐the‐horizon communication systems; however, it is unreachable by most direct measurement techniques such as balloons and satellites. Fortunately, the D region, combined with Earth's surface, forms what is known as the Earth‐Ionosphere waveguide allowing VLF and low frequency (LF) radio waves to propagate to global distances. By measuring these signals, we can estimate a path measurement of the electron density, which we assume to be a path‐averaged electron density profile of the D region. In this work, we use path‐averaged inferences from lightning‐generated radio atmospherics (sferics) with a tomographic inversion to produce 3D models of electron density over the Southeastern United States and the Gulf of Mexico. The model begins with two‐dimensional great circle path observations, each of which is parameterized so it includes vertical profile information. The tomography is then solved in two dimensions (latitude and longitude) at arbitrarily many altitude slices to construct the 3D electron density. We examine the model's performance in the synthetic case and determine that we have an expected percent error better than 10% within our area of interest. We apply our model to the 2017 “Great American Solar Eclipse” and find a clear relationship between sunlight percentage and electron density at different altitudes.

Radio Frequency-Based Diagnostics for Superconducting Magnets

Operation of high-field superconducting magnets relies on diagnostic instrumentation for measuring strain, temperature, and magnetic field variations, detecting quenching, and identifying performance problems. Discrete sensor implementation is costly, requires multi-channel data acquisition systems, and sensor density is often insufficient to resolve problematic locations spatially. Distributed sensing is a viable alternative approach providing location-specific diagnostic information over single terminal output. In particular, it can be the key to quench protection of high-temperature superconductor (HTS)-based magnets where hot spots are known to form and persist before a quench. Fiber-optic technology offers distributed sensing solution for magnets but suffers from drawbacks such as fiber fragility, high costs of optical interrogators, and difficulty in differentiating between physical quantities such as temperature and strain. We propose an alternative, robust, and easily integrable way of implementing distributed sensing in magnets using radio-frequency (RF) technologies. RF Time Domain Reflectometry (TDR) technique has been around for nearly 60 years, and it is an essential diagnostic tool used in multiple areas of technology and applied research. We discuss operational principles and practical implementation of RF TDR sensors capable of detecting local variations of strain, temperature, and magnetic field through changes in RF impedance and wave propagation time. Results of cryogenic testing of our TDR sensors with HTS tape conductors are presented. The perspective of enabling a new diagnostics paradigm for high-energy physics and fusion energy applications based on distributed RF sensing is discussed.

Performance Evaluation of a Magnetic Resonance Imager with Evidence-Based Decision Making Tools.

Evidence-based decision-making tools were used to evaluate the performance of a 16-year-old 1.5T Magnetic Resonance Imager (MRI) that has been fully dedicated to clinical service in a public hospital in Mexico. The MRI age highlights the importance of regular performance evaluations to ensure that the equipment is still functioning optimally, even when the system went through an important software and hardware updated. The use of Multiple-Criteria Decision-Making is an effective method to evaluate the performance of complex systems like MR imagers. A technical global indicator was set, revealing that only 50% of available time has been used is interesting and could be further investigated to determine if there are any factors limiting the usage of the system. The good performance indicators in terms of productivity, availability, and technical aspects are encouraging and suggest that the updated software and hardware have had a positive impact on the overall performance of the system.Finally, the use of evidence-based decision-making tools to evaluate the performance of the MR imager was a successful approach and can serve as a model for other healthcare facilities to follow.Clinical Relevance- MRI is a non-invasive diagnostic test that uses a magnetic field and radiofrequency waves to obtain detailed images of internal structures of the body. Unlike X-rays and CT scans, which use ionizing radiation, MRI does not expose patients to harmful radiation, making it a safe option for diagnostic imaging. The use of MRI a valuable tool for characterizing lesions, detecting abnormalities, and monitoring disease progression and it is widely used in several medical fields, including neurology, oncology, and orthopedics, among others. Therefore, ensuring that the MRI system is working optimally is crucial for providing reliable and accurate results, which can lead to timely and appropriate treatment for patients.

RF-EMR pollution levels near kindergartens due to mobile communication towers and Wi-Fi sources

Wireless communications play a crucial role in human lives. The introduction of cellular network systems, broadband internet services and public Wi-Fi services increase the connectivity between people exponentially. These wireless networks require antenna structures to propagate carrier waves through space and these waves are located within the Radiofrequency (RF) region in the electromagnetic spectrum. The effects of these RF waves on people, especially children, and pregnant women cannot be neglected. According to the researchers, there are some adverse health issues related to thermal and non-thermal effects due to exposure to these non-ionizing radiations. In this study, RF exposure levels within the proximity of 21 selected kindergartens in the Colombo and Kandy districts were evaluated by using a high-frequency spectrum analyzer. Results of the study show a nearly 251% increase in the RF exposure levels in the kindergartens located in Colombo district relative to the kindergartens in Kandy district. As well as GSM900, GSM1800 and UMTS cellular communication bands show a higher contribution to background RF exposure than the other wireless networks. However, measured maximum electric fields and calculated specific absorption rate (SAR) values are well below the maximum permissible levels published by International Commission on Non-Ionizing Radiation Protection (ICNIRP).

Comprehensive Review on Multiresonator-Based Chipless RFID Tag

This study reviews the multi-resonator-based chipless radio frequency identification technology. Radiofrequency (RF) waves are used in a wireless data collecting technique called radio frequency identification or simply RFID to automatically identify things. RFID is a promising technology that enables the identification and tracking of objects. Because of its benefits, including cheaper cost, smaller size, and higher security, chipless Radio Frequency Identification (RFID) technology has become more and more attractive as a potential alternative to traditional RFID technology. Chipless RFID labels are minimal expense labels since they are not outfitted with ASIC. RFID transmits data between the RFID transponder, a device that carries data, and the interrogator using radio frequency (RF) waves. The system is completely passive and does not require any kind of outside power source to run. The major advantage of spectral signature-based chipless RFID is that it can encode data in both magnitude and phase. A transponder's essential parts are its transmitter, receiver, and multi-resonators. As a result, this article will evaluate different multi-resonator types, explore numerous chipless RFID applications, and discuss the basic operation of an RFID system. Additionally, this research studies the various coding systems because information coding is an essential part of this technology.

Electromagnetic Waves’ Impact on Hydraulic Conductivity of Granular Soils

Electromagnetic (EM) waves, traditionally used for purposes such as geophysical characterization, impact properties to be measured. This paper describes the effects of radio frequency (RF) waves on the hydraulic conductivity of glass beads and natural sand. A series of tests was conducted using a customized, rigid-wall, cylindrical permeameter inside a resonant cavity made of Plexiglas covered with electrically conductive transparent films. Constant-head ASTM-D2434 tests were performed to measure the samples’ hydraulic conductivity. RF stimulation was performed using a magnetically coupled loop antenna at various frequencies and input RF-power levels. The hydraulic conductivity of both natural sand and glass-bead samples increased with RF stimulation. Furthermore, the measurement of the electric field component of RF waves was also performed to illustrate the pattern of the electric field, as well as evaluate RF’s impact on the hydraulic conductivity tests. The electric field was numerically simulated and validated against experimentally measured electric fields. A finite-difference numerical model was developed in MATLAB to analyze the seepage flow, which was then validated against the experimental results. An optimization scheme was then used to develop a governing equation for RF’s impact on hydraulic conductivity.

Radio Wave Energy Harvesting Model of a Maritime Automatic Identification System

Radio waves, the spectrum of the electromagnetic waves, are all around us and in most cases have only one purpose. The maritime Automatic Identification System (AIS) uses Very High Frequency (VHF) radio waves for the purpose of data exchange between ships and shore stations. These data exchanges take place during certain time intervals, resulting in intermittent emission of electromagnetic waves. In the research presented in this paper, the objective was to add a new purpose for the AIS electromagnetic waves, i.e. to act as a power source for the RF energy harvester. After collecting the electromagnetic waves of the AIS system, the signals’ voltage is rectified, amplified and delivered to the load. In this paper, the process of radio wave energy harvesting is simulated in the Multisim software and analyzed in detail. The results of the analysis showed a multiple increase in the voltage value at the output of the RF energy harvester.

A finite element procedure for time-dependent radio-frequency sheaths based on a two-dimensional microscale fluid model

In this paper, we present a finite element scheme for the analysis of time-dependent radio-frequency (RF) sheath behavior in a plasma-filled domain bounded by periodically curved plates. This numerical scheme is based on a two-dimensional (2D) microscale model in which the time-dependent cold-ion fluid equations, the Maxwell–Boltzmann relation for electrons, and Poisson's equation are solved subject to periodic boundary conditions (BCs) and conducting-wall BCs. The continuity of the total current is employed in localized regions to provide a constraint on the reference sheath potential. The primary purpose of this work is to understand 2D dynamic sheath behavior in order to improve predictive capabilities for RF wave interactions in magnetic fusion experiments. In particular, this work treats cases where the local radius of curvature of the wall surface is comparable to the non-neutral sheath width. Using the developed numerical code, the dependences of the ion, electron, and displacement admittances on the wall bump height, ion magnetization, ion mobility, and the magnetic field angle are investigated. It is shown that the ion and electron admittances are nearly unchanged over wide ranges of the bump height and ion magnetization. In addition, the 2D sheath effects are assessed through the spatial distributions of various quantities such as the electron density, electrostatic potential, ion velocity, and surface wall current.

SARS-CoV-2 Inactivation in Aerosol by Means of Radiated Microwaves.

Coronaviruses are a family of viruses that cause disease in mammals and birds. In humans, coronaviruses cause infections on the respiratory tract that can be fatal. These viruses can cause both mild illnesses such as the common cold and lethal illnesses such as SARS, MERS, and COVID-19. Air transmission represents the principal mode by which people become infected by SARS-CoV-2. To reduce the risks of air transmission of this powerful pathogen, we devised a method of inactivation based on the propagation of electromagnetic waves in the area to be sanitized. We optimized the conditions in a controlled laboratory environment mimicking a natural airborne virus transmission and consistently achieved a 90% (tenfold) reduction of infectivity after a short treatment using a Radio Frequency (RF) wave emission with a power level that is safe for people according to most regulatory agencies, including those in Europe, USA, and Japan. To the best of our knowledge, this is the first time that SARS-CoV-2 has been shown to be inactivated through RF wave emission under conditions compatible with the presence of human beings and animals. Additional in-depth studies are warranted to extend the results to other viruses and to explore the potential implementation of this technology in different environmental conditions.

#2665 EFFECT OF RENAL DENERVATION ON THE PLASMA LEPTIN CONCENTRATION IN PATIENTS WITH RESISTANT HYPERTENSION

Abstract Background and Aims Leptin is mainly produced by adipose tissue and has hypertensinogenic properties. In patients with arterial hypertension, plasma concentration of leptin is higher than in healthy subjects. Percutaneous ablation of the sympathetic nervous system fibers located in the wall of the renal arteries by radio frequency waves (renal denervation - RDN), was introduced as a method of invasive treatment of resistant arterial hypertension. The aim of this single center, interventional, clinical study was to assess the effect of RDN on the plasma leptin concentration in patients with resistant arterial hypertension. Method Eighteen patients (9 women, 9 men) aged 53.2±6.5 years with resistant hypertension who underwent RDN using Simplicity catheters (Medtronic, Inc., Northridge, CA) were enrolled in the study. Plasma leptin concentration was determined using the Human Leptin RIA HL-81K (Linco Research, Inc., Missouri, USA) before RDN denervation and 6 months after RDN. Additionally, patients were divided into two subgroups: responders (systolic and diastolic blood pressure - BP reduction 6 months after RDN >25 mmHg and >12 mmHg, respectively; n=9) and low responders (systolic and diastolic BP reduction 6 months after RDN ≤25 mmHg and ≤12 mmHg, respectively; n=9). Results Systolic and diastolic BP was significantly reduced after RDN (196.6±28.2 and 162.9±15.6; p<0.001 and 117.9±26.4 and 90.7±8.6 mmHg; p<0.001, respectively). Body mass index (BMI) before RDN and 6 months after RDN was similar (31.0±4.4 and 31.3±4.4 kg/m2; P = .8, respectively). Mean plasma leptin concentration before RDN and 6 months after RDN did not change significantly in the entire studied group (27.2±14.3 and 24.6±13.1 [ng/mL], NS), as well as both in responders (29.9±14.4 and 28.2±12.9 [ng/mL, NS) and low-responders subgroups (24.4±14.7 and 21.0±12.9 [ng/mL], NS), respectively. Conclusion Renal denervation is effective in the treatment of patients with resistant hypertension, however this effect is not mediated by the influence on plasma leptin concentration.

EFFECT OF RENAL DENERVATION ON THE PLASMA ADIPONECTIN CONCENTRATION IN PATIENTS WITH RESISTANT HYPERTENSION

Objective: Adiponectin is produced by white adipose tissue and has anti-diabetic, anti-atherosclerotic, anti-thrombotic, anti-inflammatory, and cardioprotective properties. In patients with arterial hypertension plasma concentration of adiponectin is lower than in healthy subjects. Renal denervation (RDN) i.e. percutaneous ablation of fibers from the sympathetic nervous system located in the wall of the renal arteries by radio frequency waves, is a method of resistant arterial hypertension treatment. The aim of this single center, interventional, clinical study was to assess the effect of RDN on the plasma adiponectin concentration in patients with resistant arterial hypertension. Design and method: Twenty-six patients (12 women, 14 men) aged 54.0±7.8 years with resistant hypertension who underwent RDN using Simplicity catheters (Medtronic, Inc., Northridge, CA) were enrolled in the study. Plasma adiponectin concentration was determined using the Human Adiponectin ELISA Kit (Otsuka Pharmaceutical Co, Tokyo, Japan) before the RDN and 6 and 12 months after this procedure. Results: Blood pressure (BP) values before RDN and 6 and 12 months after RDN were as follow: systolic BP - 190.4±24.5, 160.8±14.5, 155.7±17.9 mmHg (p<0.001) and diastolic BP - 111.7±18.9, 88.9±8.3, 91.2±10.2 mmHg (p<0.001), respectively. Body mass index (BMI) before RDN, 6 and 12 months after RDN were 31.5±4.2, 30.5 ±4.4, 30.2±4.0 kg/m2, (p = 0.057), respectively. Plasma adiponectin concentration before the RDN and 6 and 12 months after RDN were 6.93±4.85, 7.94±3.97, 8.83±6.12 [μg/ml] (p = 0.007), respectively. In the follow up i.e. 6 and 12 months after RDN plasma adiponectin concentration increases significantly in responders (systolic BP decrease higher or equal 25 mmHg) (7.93±6.14, 8.87±4.68, 10.57±7.51 [μg/mL]; respectively]; p = 0.03, and did not change significantly in low-responders to RDN (systolic BP decrease < 25 mmHg) (5.76±2.45, 6.86±2.76, 6.81±3.19 [μg/mL]; respectively; p = 0.2). Conclusions: 1. Plasma adiponectin concentration increases significantly after successful RDN in patients with resistant arterial hypertension. 2. Higher plasma adiponectin concentration may participate - beyond blood pressure reduction - in the cardiovascular benefits related to successful RDN, however clinical consequences of our results need further investigations.

Multicenter study to evaluate the efficacy and standardize radiofrequency ablation therapy for early breast cancer.

e12570 Background: Early-stage breast cancer is increasingly detected by screening mammography, and we aim to establish radiofrequency ablation therapy (RFA) as a minimally invasive, cost-efficient, and cosmetically acceptable local treatment. In our Phase I study, localized tumors with a maximum diameter of 2 cm, preoperatively diagnosed by imaging and histopathology, were treated with RFA. A 90% complete ablation rate was confirmed histopathologically. Our phase II multicenter study of RFA without resection for early breast cancer will evaluate the long-term safety and efficacy of RFA as well as its cosmetic results, which are a perceived advantage of this technique. Methods: From Nov. 2009 to Nov. 2012, 58 patients with early-stage breast cancer received non-surgical RFA therapy. Patients had localized solitary N0 tumors with a maximum diameter of 1 cm. In our experimental therapy, a radiofrequency electrode needle is inserted through the skin into the breast lesion under imaging guidance, followed by thermal ablation with radiofrequency waves. RFA will be conducted under general anesthesia. The Cool-tip™ RF Ablation Single Electrode Kit (Medtronic, CO, USA) will be used to standardize the evaluation of the ablation effect. They underwent RFA and SNB under general anesthesia and adjuvant therapy and breast radiation. Follow-up evaluation for residual tumor at 3, 6, and 12 months after RFA included clinical examination, diagnostic imagings and vacuum-assisted biopsy. Surgical resection was recommended for patients with suspected residual disease or incomplete ablation. The primary endpoint was the frequency of adverse events. Secondary endpoints included the complete ablation rate and ipsilateral breast relapse-free rate. Results: The follow-up period ranged from 15 to 109 months (median, 85 months). The 57 patients completed the non-surgical RFA procedure and underwent diagnostic imaging and needle biopsy after 3 months. Seven patients with suspected incomplete ablation underwent surgical resection; incomplete ablation was confirmed in 5 (8.6%, 2 with invasive and 3 with non-invasive ductal carcinoma). During subsequent follow-up, 1 patient each was diagnosed with contralateral breast cancer and ipsilateral breast tumor relapse. No distant recurrence was documented. Cosmetic results were excellent in 94% of patients. Conclusions: Our phase II multicenter study of RFA without resection for early breast cancer will evaluate the long-term safety and efficacy of RFA as well as its cosmetic results, which are a perceived advantage of this technique. Clinical trial information: UMIN000008675 .

A Portable Non-Invasive Electromagnetic Lesion-Optimized Sensing Device for the Diagnosis of Skin Cancer (SkanMD).

The article presented herein proposes an alternative skin cancer screening method that delivers non-invasive diagnosis and monitoring of skin lesions by leveraging electromagnetic waves with radio frequency technology and circuits. The proposed handheld device, named SkanMD, comprises a sensitive electromagnetic sensor, customized radio frequency wave analyzer circuits, and machine learning algorithms. The device is used in clinical studies that are performed on a total of 46 individuals that are composed of 18 patients with pre-diagnosed skin cancer, 10 individuals with benign nevi, 7 patients with arbitrary diseases, and 11 healthy individuals. These studies included the measurement of the reflection coefficient, S11, on multiple skin regions and recording the obtained complex values to build a Support Vector Machine (SVM)-based classification model. Due to the lesion-optimized sensor and the unified cross-patient classifier, our results differentiate between cancerous and non-cancerous skin lesions with a sensitivity that exceeds 92% and a specificity that exceeds 81.4%. These reported results are based on a limited population size study. They also demonstrate that SkanMD is a promising solution that could augment conventional diagnosis methods to greatly improve patient comfort and enable instantaneous and accurate diagnosis.

Chemotherapy and radiofrequency hyperthermia (oncothermia) in the treatment of metastatic colorectal cancer.

e15569 Background: Colorectal cancer (CRC) is the second leading cause of death in adults. Standard treatment for metastatic disease includes chemotherapy and biological agents. Although more than 50% of patients respond to multi agent chemotherapy, resistance to treatment is a significant problem and more than 85 % of patients die within five years. Radiofrequency hyperthermia (Oncothermia- OT) is a non-invasive treatment modality which utilizes 13 MHz external radiofrequency waves to selectively heat cancer cells to 45 C, contributing to apoptosis, and aggregation of DNA repair enzymes, potentially overcoming resistance and improving chemotherapy efficacy. It has been used alone or in combination with chemotherapy. Since most metastatic CRC patients have disease limited to the abdominal cavity and liver, Oncothermia can be applied with a single electrode covering the entire abdominal cavity, immediately following chemotherapy without additional side effects. Methods: We treated 25 consecutive CRC patients with disease limited to liver and/or abdominal cavity with chemotherapy and biological agents and concomitant weekly OT (Oncotherm-EHY 3010) for one hour to the whole abdomen. Chemotherapy was FOLFIRI in 2, FOLFOX in 6, FOLFIRINOX in 17. Bevacizumab was used with chemotherapy in 22 and cetuximab in 1 patient. Patients were followed by periodic CT/MRI/PET-CT. Treatment duration ranged from 4 to 60 months. Results: No unexpected or grade III-IV toxicity was observed. Complete response was observed in 3 patients, partial response in 21 patients and stable disease in one patient for an objective response rate of 96%. Median follow up is 20.1 months (range 4-82+ months). 16 patients are alive, 3 with no disease and 13 on treatment. 9 patients have died. Conclusions: Although this is a single center retrospective observation, the combination of chemotherapy with Oncothermia appears tolerable and feasible in metastatic CRC. Despite the limitations of this observation, activity of this multi-modality treatment appears promising. Prospective randomized trials are needed to confirm these findings.

Preliminary study of radio frequency waves in hypervelocity impact plasma

Orbital debris and meteoroids can cause mechanical and electrical anomalies by impacting spacecraft. Although mechanical damage tends to occur only from particles with masses >10−3g, electrical damage can be a result of hypervelocity (> 10 km/s) impacts (HVI) even with smaller particles. In HVI, the projectile speed exceeds the speed of sound in the material and has enough energy to create plasma by ionizing the material near the surface, which can then emit radio frequency (RF) waves.In this paper, we conduct a preliminary study on the characteristics of impact-generated RF emission with the ultimate goal of building an RF predictive model for risk assessment of HVI electrical effects that can damage spacecraft. First, we introduce wavelet analysis as a method for denoising and quantifying the total RF signal energy. An appropriate mother wavelet and the number of decomposition levels are selected using a synthetic signal. Second, the total energy of the RF emission is calculated using Parseval's theorem. Results suggest that the total RF signal energy is proportional to the energy flux of the impactor. Finally, spectrograms of the RF emission are analyzed to characterize features that can be used in the future to predict impacts that can cause electrical damage to satellites.

Experimental study of core MHD events in thousand-second improved confinement plasma on the EAST tokamak

Recently, stationary plasma with a world-record pulse length of 1056 s was achieved on the Experimental Advanced Superconducting Tokamak (EAST). In this work, the core magnetohydrodynamics (MHD) events as well as mode coupling processes have been investigated in EAST long pulse operation with electron heating dominant and pure radio frequency wave heating low collisionality, by using several diagnostics and the nonlinear numerical code M3D together. A saturated m/n = 1/1 kink mode was observed in the core region, where a stable internal transport barrier was found in the electron temperature channel. The frequencies and 2D structures of these modes were studied by a combination of soft X-ray (SXR) imaging and electron cyclotron emission diagnostics. The frequency of the m/n = 1/1 mode exhibited a feature of chirping down with time, and this chirping rate corresponds to the rate of electron diamagnetic drift frequency change. A twisted pattern (‘Taichi structure in shape’) was reconstructed by SXR tomography of the m/n = 1/1 mode. The perturbations of electron temperature and density caused by m/n = 1/1 are different in size, the latter one being much smaller. The destabilization of m/n = 1/1 was due to the strong central heating combined with electron cyclotron resonance heating and lower hybrid current drive. In the presence of the m/n = 1/1 mode, a negative current was generated on the magnetic axis, which anomalously broadened the core current profile. A m/n = 3/2 tearing mode triggered by m/n = 1/1 mode was also observed. The m/n = 3/2 mode has a smaller frequency than the m/n = 1/1 mode, and carries an m/n = 3/2 island with detectable size. A novel 3D MHD model that separately evolves the plasma density and temperature is applied to the m/n = 3/2 triggered by m/n = 1/1. It is found that a toroidal current density at the q = 1.5 surface, caused by non-axisymmetric density perturbation during the m/n = 1/1 nonlinear growth phase, was generated and hence the destabilization of the m/n = 3/2 tearing mode. Both the modeled electron temperature and density perturbations agree well with experimental observations. In the last section of this paper, the interaction between the m/n = 1/1 mode and fast electrons as well as the active control of this mode are also presented.

Spin Hall effect of radiofrequency waves in magnetized plasmas.

In inhomogeneous media, electromagnetic-wave rays deviate from the trajectories predicted by the leading-order geometrical optics. This effect, called the spin Hall effect of light, is typically neglected in ray-tracing codes used for modeling waves in plasmas. Here, we demonstrate that the spin Hall effect can be significant for radiofrequency waves in toroidal magnetized plasmas whose parameters are in the ballpark of those used in fusion experiments. For example, an electron-cyclotron wave beam can deviate by as large as 10 wavelengths (∼0.1m) relative to the lowest-order ray trajectory in the poloidal direction. We calculate this displacement using gauge-invariant ray equationsof extended geometrical optics, and we also compare our theoretical predictions with full-wave simulations.

The effect of plasma beta on error-field penetration in radio-frequency wave heated plasmas in EAST

The plasma-beta effect on the n = 1 resonant magnetic perturbation (RMP) field penetration in purely radio-frequency (RF) wave heated discharges has been investigated in EAST. The experimental results show that the dependence of the threshold RMP coil current for field penetration, , on the total absorbed power P tot scales as approximately , indicating that the error-field tolerance is improved with increasing RF power. This is benefited by the increased electron perpendicular flow dominated by a counter-current electron diamagnetic flow with increasing RF power. However, theoretical scaling in cylindrical geometry overestimates the power index. Assuming an additional term for the normalized beta in the scaling, it is shown that the fitted from the experimental observation is around −1, indicating a degradation effect of plasma beta. To clarify the underlying physics of the plasma-beta effect that was not included in the theoretical scaling in cylindrical geometry, the MARS-Q code with full toroidal geometry is employed for simulation of nonlinear field penetration (Liu et al 2013 Phys. Plasmas 20 042503). The MARS-Q simulation results reproduce the dependence well, and hence the P tot scaling of the threshold current in experimental observations. The main reason for this is that the net total torque, which is mainly contributed by the neoclassical toroidal viscosity (NTV), increases with increasing plasma . The results demonstrate that the nonlinear toroidal coupling effect via NTV torque plays an important role in determining field penetration, even in cases with relatively low , which is far less than the no-wall beta limit.