Acceleration Environment Research Articles

RLG SINS Dynamic Error Compensation under Vibration Environments

The dither axis bending occurs in the presence of input acceleration acting on the laser block of the ring laser gyro (RLG) due to the limited transverse stiffness of the dither motor, which will cause g-sensitive misalignments under vibration environments. A novel RLG SINS dynamic error compensation method is proposed under vibration environments in this paper. G-sensitive misalignment model of the RLG unit is developed. The equivalent gyro drift model under rotation and acceleration environments is deduced to describe the dynamic error. Optimized vibration experiments are conducted to estimate the unknown parameters. Vibration experiment results prove the validity of this method.

Analysis of Vibratory Data Collected by the Space Acceleration Measurement System (SAMS) on Blue Origin, June 19, 2016

Abstract On Sunday, June 19, 2016, a Space Acceleration Measurement System triaxial sensor head flew on a suborbital flight aboard Blue Origin's New Shepard vehicle to collect precision vibratory accelerometry data. The Space Acceleration Measurement System (SAMS) sensor head was mounted inside of a Blue Origin single payload locker inside of the crew capsule. This paper describes the configuration, capture, and analysis of the SAMS data from this flight along with other, related flight log information provided by Blue Origin. Three overlapping periods during the flight were identified and characterized to provide future users of the platform with insight into options that may prove suitable for their research needs. Average accelerations in the Post-Separation Period were consistent with other low-g research platforms, while the shorter Microgravity Period in the middle of the flight showed ultra-quiet vibratory acceleration environments. Researchers can consider this microgravity quality versus time a tradeoff in their experimental designs.

Monte Carlo Evaluation of Single Event Effects in a Deep-Submicron Bulk Technology: Comparison Between Atmospheric and Accelerator Environment

In this work, the expected SEE rate in a generic model of a state-of-the-art SRAM memory was studied as a function of the critical charge in different radiation environments. The FLUKA Monte Carlo code was used to evaluate the SEE mono-energetic cross section for different particles as well as the SEE rate in different mixed field environments through an energy deposition analysis. Mono-energetic cross sections for protons and both positively and negatively charged muons were evaluated in the 0.1–1000 MeV energy range. The SEE rate was calculated for different mixed radiation field environments such as the terrestrial environment, commercial flight altitude, LHC critical areas for electronics and CERN’s CHARM test facility. Results show that direct ionization from charged particles becomes predominant between 0.2-1.1 fC compared to indirect neutron energy deposition. Finally the CHARM facility was demonstrated to be able to reproduce with a good approximation both the atmospheric and accelerator environments, particularly with regard to avionics, ground level applications and LHC.

Effect of Biological Pollutant on Outdoor Polymer Insulator Under Acceleration Environment Condition

This study deals with the investigation on the effect of mineral contaminant and microbiological pollutant on outdoor polymer insulator. An experimental setup using pre-conditioned salt fog test is used to accelerate the desired environmental condition required by the pollutant to grow. As result, the effect of mineral contaminant on the growth of microbiological pollutant in the polymer insulator can be analyzed in a faster manner. Chlorella vulgaris as microbiological pollutant was successfully cultivated on 24 kV polymer insulators in a controlled environmental condition. The analysis is presented by comparing the performances between pre-conditioned and normal insulators. A scanning electron microscope (SEM) test is also performed to determine the growth of chlorella vulgaris. Some leakage current and breakdown voltage measurement tests were conducted to determine the insulation performance of insulators. SEM results show that chlorella vulgaris layer did not grow on the normal insulators. Meanwhile chlorella vulgaris layer was formed up to of 30.5 μm depth inside pre-conditioned insulator surface. The test at 40 kV ac voltage shows up to 0.23 mA leakage current was detected on pre-conditioned insulators. The degradation of breakdown voltage of 12.5 % was detected after 8 weeks treatment.

Suitable configurations for triangular formation flying about collinear libration points under the circular and elliptic restricted three-body problems

The design of formations of spacecraft in a three-body environment represents one of the most promising challenges for future space missions. Two or more cooperating spacecraft can greatly answer some very complex mission goals, not achievable by a single spacecraft. The dynamical properties of a low acceleration environment such as the vicinity of libration points associated to a three-body system, can be effectively exploited to design spacecraft configurations able of satisfying tight relative position and velocity requirements. This work studies the evolution of an uncontrolled formation orbiting in the proximity of periodic orbits about collinear libration points under the Circular and Elliptic Restricted Three-Body Problems. A three spacecraft triangularly-shaped formation is assumed as a representative geometry to be investigated. The study identifies initial configurations that provide good performance in terms of formation keeping, and investigates key parameters that control the relative dynamics between the spacecraft within the three-body system. Formation keeping performance is quantified by monitoring shape and size changes of the triangular formation. The analysis has been performed under five degrees of freedom to define the geometry, the orientation and the location of the triangle in the synodic rotating frame.

Beam Induced Hydrodynamic Tunneling in the Future Circular Collider Components

A future circular collider (FCC) has been proposed as a post-Large Hadron Collider accelerator, to explore particle physics in unprecedented energy ranges. The FCC is a circular collider in a tunnel with a circumference of 80\char21{}100 km. The FCC study puts an emphasis on proton-proton high-energy and electron-positron high-intensity frontier machines. A proton-electron interaction scenario is also examined. According to the nominal FCC parameters, each of the 50 TeV proton beams will carry an amount of 8.5 GJ energy that is equivalent to the kinetic energy of an Airbus A380 (560 t) at a typical speed of $850\text{ }\mathrm{km}/\mathrm{h}$. Safety of operation with such extremely energetic beams is an important issue, as off-nominal beam loss can cause serious damage to the accelerator and detector components with a severe impact on the accelerator environment. In order to estimate the consequences of an accident with the full beam accidently deflected into equipment, we have carried out numerical simulations of interaction of a FCC beam with a solid copper target using an energy-deposition code (fluka) and a 2D hydrodynamic code (big2) iteratively. These simulations show that, although the penetration length of a single FCC proton and its shower in solid copper is about 1.5 m, the full FCC beam will penetrate up to about 350 m into the target because of the ``hydrodynamic tunneling.'' These simulations also show that a significant part of the target is converted into high-energy-density matter. We also discuss this interesting aspect of this study.

Effect of passengers’ active head tilt and opening/closure of eyes on motion sickness in lateral acceleration environment of cars

This study examined the effect of passengers’ active head-tilt and eyes-open/eyes-closed conditions on the severity of motion sickness in the lateral acceleration environment of cars. In the centrifugal head-tilt condition, participants intentionally tilted their heads towards the centrifugal force, whereas in the centripetal head-tilt condition, the participants tilted their heads against the centrifugal acceleration. The eyes-open and eyes-closed cases were investigated for each head-tilt condition. In the experimental runs, the sickness rating in the centripetal head-tilt condition was significantly lower than that in the centrifugal head-tilt condition. Moreover, the sickness rating in the eyes-open condition was significantly lower than that in the eyes-closed condition. The results suggest that an active head-tilt motion against the centrifugal acceleration reduces the severity of motion sickness both in the eyes-open and eyes-closed conditions. They also demonstrate that the eyes-open condition significantly reduces the motion sickness even when the head-tilt strategy is used.Practitioner Summary: Little is known about the effect of head-tilt strategies on motion sickness. This study investigated the effects of head-tilt direction and eyes-open/eyes-closed conditions on motion sickness during slalom automobile driving. Passengers’ active head tilt towards the centripetal direction and the eyes-open condition greatly reduce the severity of motion sickness.

Neutron Spectrometry and Dosimetry Using CR-39 Detectors

Solid polymeric track detectors (SPTDs), due to their insensitivity to low LET radiations and integrating nature of signal registration, are found to be effective and convenient for neutron measurements, particularly in pulsed and mixed radiation fields such as in particle accelerator environments. This paper in addition to reviewing some of the existing methods of neutron spectrometry and dosimetry, explores new approaches on the use of SPTDs for neutron measurements, elaborates on the extended energy response and rapid etching techniques of SPTDs along with some new results. Microwave induced chemical etching (MICE) technique, recently introduced for rapid and efficient processing of track detectors is discussed in the paper.Contents of Paper

Restraint harness performance during flight maneuvers: a parametric study.

Modern super agile fighter aircraft are capable of producing an increasing multiaxial acceleration environment which can adversely affect the pilot. An evaluation of the performance of the restraint system during flight maneuvers will benefit restraint designs and, thus, the safety of pilots. A finite element model of a mannequin with PCU-15/P harness restraint was used in this study to investigate how the factors, such as strap material stiffness, friction, and belt tension, affect the performance of restraint systems during impact along the -Gx, -Gy, and -Gz directions. The corresponding maximum displacement of the mannequin's torso was computed. The mannequin moved beyond 74 mm sideways. The change in friction coefficient (FC) from 0.1 to 0.4 decreased the displacement of the lower torso by less than 6.7%. The displacement of the torso decreased as the stiffness of the strap or tension increased. Displacement decreased by 9.3%, 6.0%, and 2.7% for the lower torso under the Gx impact, as the tightening force increased from 20 N to 80 N gradually. However, this changed slightly when the stiffness arrived at 1 E or the tension increased to 60 N. PCU-15/P harness has the poorest performance during side impact and friction plays an unimportant role in affecting its performance. The stiffness of the webbing used in the PCU-15/P harness is sufficiently high. The lap belt has more effect on limiting the movement of the pilot than the shoulder straps, and a tension of 60 N during the adjustment may be enough for conventional flight maneuvers.

Demonstration of the stabilization technique for nonplanar optical resonant cavities utilizing polarization.

Based on our previously developed scheme to stabilize nonplanar optical resonant cavities utilizing polarization caused by a geometric phase in electromagnetic waves traveling along a twisted path, we report an application of the technique for a cavity installed in the Accelerator Test Facility, a 1.3-GeV electron beam accelerator at KEK, in which photons are generated by laser-Compton scattering. We successfully achieved a power enhancement of 1200 with 1.4% fluctuation, which means that the optical path length of the cavity has been controlled with a precision of 14 pm under an accelerator environment. In addition, polarization switching utilizing a geometric phase of the nonplanar cavity was demonstrated.

In-situ measurements of the secondary electron yield in an accelerator environment: Instrumentation and methods

The performance of a particle accelerator can be limited by the build-up of an electron cloud (EC) in the vacuum chamber. Secondary electron emission from the chamber walls can contribute to EC growth. An apparatus for in-situ measurements of the secondary electron yield (SEY) in the Cornell Electron Storage Ring (CESR) was developed in connection with EC studies for the CESR Test Accelerator program. The CESR in-situ system, in operation since 2010, allows for SEY measurements as a function of incident electron energy and angle on samples that are exposed to the accelerator environment, typically 5.3GeV counter-rotating beams of electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY with discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. The samples can be exchanged without venting the CESR vacuum chamber. Measurements have been done on metal surfaces and EC-mitigation coatings. The in-situ SEY apparatus and improvements to the measurement tools and techniques are described.

Dynamic Modeling of a High-Dynamic Flight Simulator

High-dynamic flight simulator (HDFS), using a centrifuge as its motion base, is a machine utilized for simulating the acceleration environment associated with modern advanced tactical aircrafts. This paper models the HDFS as a robotic system with three rotational degrees of freedom. The forward and inverse dynamic formulations are carried out by the recursive Newton-Euler approach. The driving torques acting on the joints are determined on the basis of the inverse dynamic formulation. The formulation has been implemented in two numerical simulation examples, which are used for calculating the maximum torques of actuators and simulating the time-histories of kinematic and dynamic parameters of pure trapezoid Gz-load command profiles, respectively. The simulation results can be applied to the design of the control system. The dynamic modeling approach presented in this paper can also be generalized to some similar devices.

OBSERVATION OF HIGH IRON CHARGE STATES AT LOW ENERGIES IN SOLAR ENERGETIC PARTICLE EVENTS

The ionic charge states of solar energetic particles (SEPs) provide direct information about the source plasma, the acceleration environment, and their transport. Recent studies report that both gradual and impulsive SEP events show mean iron charge states Q Fe ~ 10-14 at low energies E ≤ 0.1 MeV nuc–1, consistent with their origin from typical corona material at temperatures 1-2 MK. Observed increases of Q Fe up to 20 at energies 0.1-0.5 MeV nuc–1 in impulsive SEPs are attributed to stripping during acceleration. However, Q Fe > 16 is occasionally found in the solar wind, particularly coming from active regions, in contrast to the exclusively reported Q Fe ≤ 14 for low energy SEPs. Here we report results from a survey of all 89 SEP events observed with Advanced Composition Explorer Solar Energetic Particle Ionic Charge Analyzer (SEPICA) in 1998-2000 for iron charge states augmented at low energy with Solar and Heliospheric Observatory CELIAS suprathermal time-of-flight (STOF). Nine SEP events with Q Fe ≥ 14 throughout the entire SEPICA and STOF energy range have been identified. Four of the nine events are impulsive events identified through velocity dispersion that are consistent with source temperatures ≥2 MK up to ~4 MK. The other five events show evidence of interplanetary acceleration. Four of them involve re-acceleration of impulsive material, whose original energy dependent charge states appear re-distributed to varying extent bringing higher charge states to lower energy. One event, which shows flat but elevated Q Fe ~ 14.2 over the entire energy range, can be associated with interplanetary acceleration of high temperature material. This event may exemplify a rare situation when a second shock plows through high temperature coronal mass ejection material.

Development of a 4-mirror optical cavity for an inverse Compton scattering experiment in the STF

To obtain high-brightness quasi-monochromatic X-rays via inverse Compton scattering (ICS), an optical cavity for intensifying laser beams was designed and implemented in a new beam line at the KEK Superconducting RF Test Facility (STF) accelerator. The optical cavity adopts a planar configuration consisting of 4 mirrors. This confocal type resonator provides stable laser storage even with a long mirror distance, enabling head-on collision with the electron beams. To overcome the well-known astigmatism problems of the planar-type optical cavity, two forcibly bendable cylindrical mirrors were introduced instead of flat mirrors. With this new function for laser profile adjustment, an almost round laser profile at the waist point in the accelerator environment was successfully achieved. Estimated waist sizes were 43.7μm for the horizontal and 50.8μm for the vertical dimensions. The feedback control of this 4-mirror optical cavity worked with a stiff plate supporting all 4 mirrors. 1.7×103 finesse and 2.8-kW stored power for a 1-ms duration with 5Hz were achieved.

The practical use of an interactive visualization and planning tool for intervention planning in particle accelerator environments with ionizing radiation

A core issue during the planning of a maintenance intervention in a facility with ionizing radiation is the minimization of the integrated equivalent dose contracted by the maintenance workers during the intervention. In this work, we explore the use of a technical-scientific software program facilitating the intervention planning in irradiated environments using sound mathematical concepts. We show how the software can be used in planning future operations using a case studies: the decommissioning of a beam dump for a linear 160MeV H− accelerator. Interactive visualization of the facilities and radiation levels, as well as tools for interactive trajectory planning are explored, as well as automatic calculation of the expected integrated individual dose contracted during an intervention.

束流诊断虚拟加速器环境开发

Gu Duan(谷端) ;1) Zhang Meng(张猛) Gu Qiang(顾强) Huang Dazhang(黄大章) Zhao Minghua(赵明华) 1 Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China 2 University of Chinese Academy of Sciences, Beijing 100049, China Abstract:For the proper operation of Dalian Compact Light Source (DCLS) linac, measurement and control of the electron bunch is critical. In order to test control algorithms and high level physical applications, a virtual accelerator environment is constructed based on ELEGANT and SDDS toolkit. The required beam parameter measurement and orbit control tools are verified under this virtual environment. The design concept and current development status are presented.

Flexible and Robust Multilayer Micro-Vibrational Harvesters for High Acceleration Environments

This paper presents the fabrication and characterization of multilayer PVDF resonant micro-vibrational energy harvesters designed to withstand environments in which high levels of acceleration are present. The multilayer cantilevers are fabricated by combining two folded PVDF stacks into a multilayered, bimorph structure. This acts to increase the overall capacitance of the harvester, a problem that plaques PVDF cantilevers as a result of its low dielectric constant. Moderate powers (7 μW) are produced from the cantilevers even at high acceleration levels (20 g) due to the limited piezoelectric coefficient of PVDF; however, as a result of the high tensile strength and low elastic modulus of PVDF, the cantilevers are able to survive extremely high accelerations (> 4000 g) without breakage – a critical problem for harvesters based on brittle piezoelectric materials and substrates.

Progress of Studies on Durability of FRP Rods Used in Civil Engineering

Fiber reinforced polymer ( FRP) rods have a broad application in civil eng ineering field used as a material substiting steelbars. Based on the domestic and abroad research, the durability of the fiber reinforced polymer (FRP) rods undermultifarious environmental conditions is summarized in this paper, and the effect of environments such as temperature, humidity, corrosion from acid, alkaline and salt solutions on durability performance of FRP materials as well as the degradation of the bond characteristics between FRP rods and the interface of concrete caused by the acceleration environment test are mainly discussed. The results indicate that the environmenta lconditionsm entioned above affect FRP rods and bond characteristics between FRP rods and the in terface of concrete.In addition, a relatedmodel predicting the influence on durability of FRP rods in alkaline solutions is given and future study trend on durability of FRP rods is presented

Acquisition technology research of EEG and related physiological signals under +Gz acceleration

With the continuous improvement of maneuvering performance of modern high-performance aircraft, the protection problem of flight personnel under high G acceleration, the development as well as research on monitoring system and the equipment for human physiological signals processing which include electroencephalogram (EEG) have become more and more important. Due to the particularity of +Gz experimental conditions, the high-risk of human experiments and the great difficulty of dynamic measurement, there is little research on the synchronous acquisition technology of EEG and related physiological signals under +Gz acceleration environment. We propose a framework to execute human experiments using the three-axial high-performance human centrifuge, develop reasonable operation mode and design a new experimental research method for EEG signal acquisition and variation characteristics on three-axial high-performance human centrifuge under the environment of +Gz acceleration. We also propose to build the synchronous real-time acquisition plan of EEG, electrocardiogram, brain blood pressure, ear pulse and related physiological signals under centrifuge +Gz acceleration with different equipments and methods. The good profiles of EEG, heart rate, brain blood pressure and ear pulse are obtained and analyzed comparatively. In addition, the FMS hop-by-hop continuous blood pressure and hemodynamic measurement system Portapres are successfully applied to the ambulatory blood pressure measure under centrifuge +Gz acceleration environment. The proposed methods establish the basis and have an important guiding significance for follow-up experiment development, EEG features spectral analysis and correlation research of all signals.

Operation of 1074 HTS Current Leads at the LHC: Overview of Three Years of Powering the Accelerator

The powering of the LHC machine relies on more than 3000 current leads transferring all together about 3 MA of current from/to the superconducting magnets. Among these leads, more than 1000 are based on high-temperature superconducting material. This paper reports on the experience gained after the first 3 years of operation in a real accelerator environment, where the leads underwent the thermal and electrical cycles required for the operation of the machine. Faulty conditions experienced during operation are also reported.