Fringing Field Effect Research Articles

Analysis of fringe field effects on measurement errors for Q-scanning-based emittance diagnosis system

As a widely recognized emittance measurement technique, the Q-scanning method typically plays a crucial role in the commissioning process of accelerator-based beam injectors. The Q-magnet, being a pivotal component, significantly influences the measurement capability, thus warranting detailed examination in this study. By reassessing the measurement outcomes of the Q-magnet, the impact of fringe fields on emittance measurement precision is thoroughly scrutinized within this framework. Subsequently, corrections to the transfer matrices of the Q-scanning system under different excitation currents are implemented by revisiting fundamental beam optic principles. Moreover, virtual measurements via both theoretical calculations and beam dynamics simulations are conducted to validate these corrections, utilizing the setup of an existing beam injector established at Huazhong University of Science and Technology. Both the theoretical and experimental results indicate that the measurement accuracy of the Q-scanning technique can be improved by correcting the fringe field effects.

Study of A Heterojunction Double Gate Ferroelectric p-n-i-n Tunnel FET combining analytical modeling and TCAD simulation

A short channel Heterojunction Double Gate Ferroelectric p-n-i-n Tunnel Field Effect Transistor structure is proposed in this article to alleviate undesirable ambipolarity and Miller Capacitance and has a steeper subthreshold swing with improvement in ON state current compared to other conventional TFET structures. This work develops a physics based relevant analytical model of surface potential with the effect of gate fringing field and inclusive source and channel depletion region, drain current model, terminal charge and capacitance model to investigate its transient performance for the impact of ferroelectric polarization according to the Miller Ferroelectric polarization model. The proposed device is also validated using the SILVACO ATLAS device simulator, which yields a good agreement with the model, establishing its reliability and acceptability. The device achieves a steeper subthreshold of 31.3 mV/decade, an improved ON current∼5.9 x 10−4A/μmand enhanced transconductance∼0.105 ms as well as a very low energy delay product (EDP)∼4.07 x 10−3Js with hysteresis free operation at a low supply voltage∼0.5 V in a 40 nm technology node, making it desirable for ultra-low power analog and logic applications.

Correction of dynamic magnetic field errors at the rapid cycling synchrotron of China Spallation Neutron Source

At a Rapid Cycling Synchrotron (RCS), dynamic magnetic field errors, such as magnetic field tracking errors and dynamic fringe field effects, can cause time-dependent tune shift during beam acceleration. If the tune shift is significant enough to pass through resonance lines, it can lead to emittance growth and beam losses. Correcting time-dependent tune shift during acceleration is crucial for a RCS. Modulating the exciting current and magnetic field of quadrupole magnets at a RCS, which are powered by resonant circuits, is challenging during the ramping process. Correcting time-dependent tune shift at a RCS poses a significant technical challenge. We have proposed a method for correcting time-dependent tune shift at the rapid cycling synchrotron of China Spallation Neutron Source (CSNS), based on waveform compensation at the quadrupole magnets. This approach involves modulating the magnetic field variation process by injecting time harmonic exciting current into the quadrupole magnets. This method has been validated during the CSNS beam commissioning and has been applied at the RCS of CSNS to correct various dynamic magnetic field errors.

Dynamic fringe field effect of the rapid ramping quadrupole magnets at a Rapid Cycling Synchrotron

For a DC quadrupole magnet, the normalized magnetic field distribution along the beam trajectory is mainly determined by the mechanical structure of the magnet and remains almost independent of the exciting current. However, the magnetic field measurement results of the Rapid Cycling Synchrotron (RCS) at the China Spallation Neutron Source (CSNS) show that the normalized magnetic field distribution along the beam trajectory varies during the exciting current ramping process for rapid ramping magnets. Consequently, for rapid ramping quadrupole magnets, there are significant differences between the dynamic and static magnetic field gradient distribution. And the changes in the distribution of the magnetic field gradient can cause time dependent tune-shifts during the exciting current ramping process. For RCS, the tune is crucial, and the shifts of tune may lead to the beam approaching the resonance line, thereby causing beam loss. The impact of the fringe field effect of the rapid ramping quadrupole magnets on beam dynamics at CSNS-RCS was detailly studied. A new method for correcting the time-dependent tune shifts caused by the dynamic field distribution, based on waveform compensation at the quadrupole magnets, has also been proposed for the RCS of CSNS. Related simulation and experiment have been conducted, and the simulation results and experimental results are consistent with theoretical study results.

Complex phase modulation of liquid crystal devices with deep learning.

A deep learning-based phase modulation method for liquid crystal (LC) devices was demonstrated. For LC devices with a single-electrode structure, achieving complex phase distributions is highly challenging. Meanwhile, multi-electrode LC devices, as pixel resolution increases and electrode size decreases, encounter issues of cumbersome modulation steps and reduced modulation accuracy during the phase modulation process. This method uses the concept of field to modulate the phase of the LC device, providing an effective phase modulation scheme. By establishing a deep learning model, it maps the phase retardation distribution of LC devices onto the electric field distribution. This method effectively mitigates the phase modulation issues arising from the fringe field effect, enabling an accurate and precise phase modulation distribution.

P‐193: Ring‐shaped circular Patch liquid crystal display structure based on fringe field effect

The liquid crystal display (LCD) continues to hold a prominent position in the display industry. These years' key research topic is the fringe field effect, which aims to improve the LCD's performance. A new LCD structure utilizing the fringe field effect has been identified as a promising solution. This structure allows for the control of the electromagnetic field of the liquid crystal cell by regulating the voltage of the ring‐shaped and circular‐patch cell (RCC). This innovative structure is comprised of nematic liquid crystals (LCs) with negative dielectric anisotropy, a two‐electrode system consisting of a ring‐shaped ITO structure on the top layer and a circular patch structure on the bottom layer, and a SiO2 porous structure. Finite element simulation tests have verified the electric field strength, transmittance, and contrast of the cell and the 2x2 matrix structure, meeting the design objectives. This breakthrough has significant potential for application in the display field.

83‐3: Inverse Design of Liquid Crystal Phase Modulators for 2D/3D Switchable Display Based on Deep Learning

The fringe field effect in liquid crystal (LC) devices can cause pixel crosstalk issues. Therefore, LC devices with multiple electrode structures require multiple calibrations to achieve an approximate distribution of the target phase modulation. At the same time, optical inverse design based on data‐driven algorithms is also a highly popular topic. This article introduces a deep‐learning approach to realize inverse phase modulation in LC devices. By adopting the deep learning method for inverse phase modulation in LC devices, can effectively alleviate the problems caused by fringe field effects and achieve more precise and accurate phase modulation distribution.

Simulation study of digital waveform-driven quadrupole mass filter operated in higher stability regions for high-resolution inductively coupled plasma mass spectrometry.

The use of a frequency-scanned digital quadrupole mass filter (QMF) with varying duty cycles shows promise for application as a high-resolution mass analyzer design for inductively coupled plasma mass spectrometry (ICP-MS). High resolution in ICP-MS is important to overcome isobaric polyatomic interferences. Here, we explore the possibility and the characteristics of using a digital quadrupole operating in higher stability regions for ICP-MS. We perform computational simulations in SIMION of a digital QMF that is operated by scanning the frequency of the digital waveform at a fixed driving voltage and various duty cycles. For ions in the atomic mass range (7-238 m/z), we investigate the expected resolution, transmission, fringe field effects, and ion trajectories. We compare different characteristics between sine and digital waveform QMF. Within the capability of current digital waveform generation technology, a digital QMF can produce variable mass resolution, from several hundred to more than 10 000. This mass resolution covers the low, medium, and high resolutions that are typical for sector-field ICP-MS. Additionally, simulations suggest that transmission of the QMF remains high at high resolution. For example, with 87.50/12.50 duty cycle (zone 4,1), resolution at 10% peak width is 10420 for m/z 80. The transmission through the quadrupole, which is constant for all isoenergetic ions, is ~2.5%, and most ion loss is due to the defocusing effects of the fringe field. Compared to sinusoidal QMFs, ions need many fewer cycles in the digital QMF to obtain high resolution. The results demonstrate that the use of a frequency-scanned, duty-cycle-modulated digital QMF as the mass analyzer for ICP-MS has the potential to produce high resolution while maintaining considerable transmission, thus overcoming most spectral interferences in elemental MS.

61‐1: The Influence of Fringing Field Effect of Liquid Crystal on Silicon Devices with Different Liquid Crystal Thickness for Telecommunication Applications

61‐1: The Influence of Fringing Field Effect of Liquid Crystal on Silicon Devices with Different Liquid Crystal Thickness for Telecommunication Applications

Open-Ended Coaxial Probe for Effective Reconstruction of Biopsy-Excised Tissues' Dielectric Properties.

Dielectric characterization is extremely promising in medical contexts because it offers insights into the electromagnetic properties of biological tissues for the diagnosis of tumor diseases. This study introduces a promising approach to improve accuracy in the dielectric characterization of millimeter-sized biopsies based on the use of a customized electromagnetic characterization system by adopting a coated open-ended coaxial probe. Our approach aims to accelerate biopsy analysis without sample manipulation. Through comprehensive numerical simulations and experiments, we evaluated the effectiveness of a metal-coating system in comparison to a dielectric coating with the aim for replicating a real scenario: the use of a needle biopsy core with the tissue inside. The numerical analyses highlighted a substantial improvement in the reconstruction of the dielectric properties, particularly in managing the electric field distribution and mitigating fringing field effects. Experimental validation using bovine liver samples revealed highly accurate measurements, particularly in the real part of the permittivity, showing errors lower than 1% compared to the existing literature data. These results represent a significant advancement for the dielectric characterization of biopsy specimens in a rapid, precise, and non-invasive manner. This study underscores the robustness and reliability of our innovative approach, demonstrating the convergence of numerical analyses and empirical validation.

Gate Electrode Work Function Engineered Nanowire FET with High Performance and Improved Process Sensitivity

MOSFETs have been used in integrated circuits for a long time. These were replaced by FinFET’s in 2011. But for short-channel devices, FinFET’s have low performance due to various effects like velocity saturation, hot carrier effect, drain-induced barrier lowering, channel length modulation, fringing field effect, sub-threshold conduction, threshold voltage roll-off, etc. Gate All Around FET (GAA FET) is the best device that will replace the FinFET’s. Therefore, during the fabrication process, it is crucial to investigate the effects of process variations caused by changes in device dimensions. This research discusses the performance of the proposed device due to process variations. The effect of changes in radius, gate oxide thickness, gate length, and channel doping on GAA FET has been discussed in detail.

Thin-body effects in double-gate tunnel field-effect transistors

Scaling down the body thickness (T b) of double-gate tunnel field-effect transistors (DG-TFETs) is helpful in suppressing short-channel effects, but it may give rise to thin-body effects (TBEs). Based on 2D device simulations, this study examines the mechanisms and influences of TBEs in DG-TFETs as T b is scaled down. Differently from previous beliefs, the on-current degradation in thin-body DG-TFETs is not mainly caused by the volume effect, but rather by a newly defined TBE named lateralization effect. This is because the lateralization of tunneling direction significantly increases tunnel width, whereas the reduction of tunneling volume is quite limited due to narrow tunneling regions. To study the T b-dependence of current, therefore, the vertical tunneling has to be taken into consideration. When considered as a TBE, the fringing field effect caused by reduction in T b is not significant in degrading the on-current of thin-body DG-TFETs because the narrow tunneling regions are strongly gate-controlled. The only TBE that enhances the on-current is the coupling effect, but its role is only significant for low-bandgap bodies in which the coupling effect can efficiently promote the tunneling towards the body center. Not as previously thought that the quantum confinement effect monotonically increased, it even decreases as T b decreases down to sub-10 nm before turning to increase, thanks to the space sharing between proximate local quantum wells. A comprehensive understanding of the TBEs is useful for providing design insight, especially for determining the optimal T b to maximize the on-current.

Design of the gradient dipole magnet for LLICTF

The Lanzhou Light Ion Cancer Therapy Facility (LLICTF) is a compact medical accelerator currently under construction. It is designed to treat cancer using a 230 MeV, 30 mA H+ beam and a 85 MeV/u, 1 mA 3He2+ beam. The facility comprises two ion sources, a low-energy beam-transport (LEBT), a Radio Frequency Quadrupole (RFQ), a medium-energy beam-transport (MEBT), and the main ring accelerating structure. Due to the presence of two ion sources, it is necessary to introduce a dipole magnet which is symmetrically focused as much as possible to meet the focusing requirements of the LEBT beam. Therefore, a gradient dipole magnet has been designed to achieve this symmetrical focusing. This paper discusses the theoretical and simulated symmetric focusing of the gradient dipole magnet. It also analyzes the effect of fringe fields and space charge. Additionally, this paper presents the results of the model design with CST and the multi-particle simulation results with TraceWin.

Dynamic fringe field effects of the rapid ramping quadrupole magnets at the Rapid Cycling Synchrotron of China Spallation Neutron Source

The dynamic fringe field of the quadruple magnets at the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS) was measured and studied using a small flip coil measurement system. For DC quadruple magnets, the normalized magnetic field distribution along the beam trajectory, which is determined by the mechanical structure of the magnet, is independent of the exciting current. However, the magnetic field measurement results at CSNS-RCS showed that the normalized magnetic field distribution along the beam trajectory varies during the exciting current ramping process for quadruple magnets. The variation of the normalized magnetic field distribution can induce a time-dependent tune during the ramping process. Therefore, in this paper, we analyzed and studied the dynamic fringe field effects of the rapid ramping quadrupole magnets at CSNS-RCS.

Reconfigurable Geometrical Phase Spatial Light Modulator Using Short‐Pitch Ferroelectric Liquid Crystals

AbstractThis article presents an approach to achieve a fast and analog geometrical phase modulation based on the optical axis rotation of the defect‐free Deformed Helix Ferroelectric Liquid Crystal (DHFLC) with a short pitch. This study demonstrates a Spatial Light Modulator (SLM) prototype with a feature size of 3 µm without Fringe Field Effect (FFE), having a phase depth of 1.9π, fast switching time (<250 µs) at a low operating voltage (<7 V), and high diffraction efficiency (>77%). The high phase modulation depth is achieved by developing DHFLC with a cone angle of up to 85˚, which is inherently immune to FFE. The ellipticity is minimized by using a compensation film that can suppress the changes in birefringence under the applied electric field. The proposed SLM is promising in applications such as a real‐time hologram and dynamic beam steering in Light Ranging and Detector (LiDAR).

Junctionless-accumulation-mode stacked gate GAA FinFET with dual-k spacer for reliable RFIC design

This study investigates how incorporating a dual-k spacer (SiO2 + HfO2) affects the RFIC design feasibility of a junctionless-accumulation-mode (JAM) stacked-gate (GS) gate-all-around (GAA) FinFET in the sub-10 nm range. The proposed device is compared with a conventional FinFET and those without a spacer, air, and a single-k spacer (SiO2). At a low voltage power supply, fringing field effects raise the proposed device's on-current by 35.34% and reduce the off-current by more than 76 times compared to conventional FinFET, thereby improving electron velocity, energy band profiles, transconductance, device efficiency, etc. Thus, the proposed device is well-suited for high-performance CMOS circuits. Further investigation shows that integrating a dual-k spacer reduces the output conductance, which boosts the intrinsic gain and early voltage by five times the value recorded for conventional FinFET. Although the cut-off frequency drops by 15.98%, the GTFP and GFP soar by 475.67% and 352.25%, respectively. Consequently, JAM-GS-GAA FinFET with dual-k spacer is an encouraging device for low-power RFIC circuits.

Study on the fringe field effects in HEPS booster

Study on the fringe field effects in HEPS booster

Exploring nonlinearity to enhance the sensitivity and bandwidth performance of a novel tapered beam micro-gyroscope

In this paper, nonlinearity is used to enhance the sensitivity and bandwidth performance of tapered beam micro-gyroscopes. Considering the electrostatic force nonlinearity and fringing field effects, the governing equations of system are derived by Euler angular transformation and Hamilton principle. The influences of parameters such as the shape factors and DC voltage on static deflection, pull-in voltage and natural frequency of tapered beam micro-gyroscope are analyzed by the Adomian decomposition method (ADM). Galerkin discretization is performed on the governing equations of the tapered beam micro-gyroscope. Frequency-response equation of the system is deduced and solved by applying the method of multi-scale (MMS). The convergence analysis of the frequency response curve is performed, and then verified by the Runge-Kutta method. Finally, the performance of the tapered beam micro-gyroscope is analyzed in terms of bandwidth, sensitivity, and calibration curve nonlinearity under the different shape factors. The maximum amplitude of response in the driving and sensing directions increases significantly with the change of shape factors of the tapered beam in the dynamics analysis. Compared with the straight beam micro-gyroscope, the tapered beam micro-gyroscope has the higher amplitude and pronounced nonlinear characteristics. Due to the electrostatic force nonlinearity, the amplitude of motion in the driving direction has a high response over a wide frequency band, while also effectively increasing the detection bandwidth. In addition, the nonlinear micro-gyroscope has less loss of sensitivity performance during damping fluctuations. Therefore, in view of the contradiction between bandwidth and sensitivity of the traditional micro-gyroscope, this paper proposes a solution from the perspective of structural design and nonlinear characteristics of the tapered beam micro-gyroscope.

Multi-purpose low energy beam transport system for light heavy-ion beam accelerator

The bore diameters of magnets and envelopes of beams in a low energy beam transport (LEBT) system should be large. The large diameter of magnet expands the fringe field as the fringe field distribution depends on the aperture size of the magnet. To avoid magnetic field interference and prevent damage, we investigate the fringe field distribution of a magnet. Further, we present two beam dynamics case studies, wherein all the requirements of a multi-purpose application system using different acceleration modes for neutron generation and implantation are satisfied. Providing energies between a few tens to hundreds of kiloelectronvolts, is an essential apparatus for material science studies in the low energy-region. Considering the fringe field effect of the developed magnets, the LEBT system has been re-designed to satisfy these requirements. We describe the magnetic field distributions in terms of beam dynamics parameters, and discuss it with regard to the two operation modes.

A high sensitivity and multi-axis fringing electric field based capacitive tactile force sensor for robot assisted surgery

This paper presents a design of multi-axis tactile force sensor using the fringe effect of an electric field between stationary patterned electrodes. The unique configuration of the electrodes consisting of four separate square-shaped sensing electrodes, with each encircled by excitation electrodes, allows to achieve enhanced fringe field effect and hence sensitivity. The proposed sensor can decouple the normal, shear and angular shear applied forces. The sensor is fabricated using low-cost rapid prototyping techniques with flexible Ecoflex 00–30 and silicone rubber RTV-528 as the elastomers for contact with the environment. An analytical model is developed that correlates the nominal capacitance of the sensor with that of the geometric dimensions of the stationary electrodes and air cavity height between the electrodes and elastomer. The force measurement ranges in the normal, shear, and angular axis are 5 N, 1.5 N, and 1 N respectively. The sensor shows a perfectly linear response, repeatability, and a low hysteresis error, thermal stability and robustness to the environmental interferences that makes it suitable to be used for force feedback in minimally invasive robotic surgery.