X-ray telescope onboard Astro-E: optical design and fabrication of thin foil mirrors

X-ray telescopes (XRT's) of nested thin foil mirrors are developed for Astro-E, the fifth Japanese x-ray astronomy satellite. Although the launch was not successful, the design concept, fabrication, and alignment procedure are summarized. The main purpose of the Astro-E XRT is to collect hard x rays up to 10 keV with high efficiency and to provide medium spatial resolution in limited weight and volume. Compared with the previous mission, Advanced Satellite for Cosmology and Astrophysics (ASCA), a slightly longer focal length of 4.5-4.75 m and a larger diameter of 40 cm yields an effective area of 1750 cm(2) at 8 keV with five telescopes. The image quality is also improved to 2-arc min half-power diameter by introduction of a replication process. Platinum is used instead of gold for the reflectors of one of the five telescopes to enhance the high-energy response. The fabrication and alignment procedure is also summarized. Several methods for improvement are suggested for the reflight Astro-E II mission and for other future missions. Preflight calibration results will be described in a forthcoming second paper, and a detailed study of images will be presented in a third paper.     

In-orbit performance of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

ASTRO-H was an X-ray astronomy satellite that the Japan Aerospace Exploration Agency (JAXA) developed to study the evolution of the universe and physical phenomena yet to be discovered. The primary scientific instrument of ASTRO-H was the Soft X-ray Spectrometer (SXS). Its detectors were to be cooled to 50 m K using a complex cryogenic system with a multistage adiabatic demagnetization refrigerator (ADR) developed by the National Aeronautics and Space Administration (NASA), and a cryogenic system developed by Sumitomo Heavy Industries, Ltd. (SHI). SHI’s cryogenic system was required to cool the ADR’s heatsink to 1.3 K or less in orbit for three years or longer. To meet these requirements, SHI developed a hybrid cryogenic system consisting of a liquid helium tank, a 4 K Joule-Thomson cooler, and two two-stage Stirling coolers.ASTRO-H was launched from Tanegashima Space Center on February 17, 2016. The initial operation of the SXS cryogenic system in orbit was completed successfully. The cooling performance was as expected and could have exceeded the lifetime requirement of three years.This paper describes results of ground tests, results of top-off filling of superfluid liquid helium just before launch, and cooling performance in orbit.     

Evaluation and optimization of the optical performance of low-concentrating dielectric compound parabolic concentrator using ray-tracing methods

We present a detailed design concept and optical performance evaluation of stationary dielectric asymmetric compound parabolic concentrators (DiACPCs) using ray-tracing methods. Three DiACPC designs, DiACPC-55, DiACPC-66, and DiACPC-77, of acceptance half-angles (0° and 55°), (0° and 66°), and (0° and 77°), respectively, are designed in order to optimize the concentrator for building fa?ade photovoltaic applications in northern latitudes (>55 °N). The dielectric concentrator profiles have been realized via truncation of the complete compound parabolic concentrator profiles to achieve a geometric concentration ratio of 2.82. Ray-tracing simulation results show that all rays entering the designed concentrators within the acceptance half-angle range can be collected without escaping from the parabolic sides and aperture. The maximum optical efficiency of the designed concentrators is found to be 83%, which tends to decrease with the increase in incidence angle. The intensity is found to be distributed at the receiver (solar cell) area in an inhomogeneous pattern for a wide range of incident angles of direct solar irradiance with high-intensity peaks at certain points of the receiver. However, peaks become more intense for the irradiation incident close to the extreme acceptance angles, shifting the peaks to the edge of the receiver. Energy flux distribution at the receiver for diffuse radiation is found to be homogeneous within ±12% with an average intensity of 520 W/m2.     

Flight model performance test results of a helium dewar for the soft X-ray spectrometer onboard ASTRO-H

ASTRO-H is a Japanese X-ray astronomy satellite, scheduled to be launched in fiscal year 2015. The mission includes a soft X-ray spectrometer instrument (SXS), which contains an X-ray micro calorimeter operating at 50 mK by using an adiabatic demagnetization refrigerator (ADR). The heat sink of the ADR is superfluid liquid helium below 1.3 K. The required lifetime of the superfluid helium is 3 years or more. In order to realize this lifetime, we have improved the thermal performance from the engineering model (EM) while maintaining the mechanical performance. Then, we have performed a thermal test of the flight model (FM). The results were that the heat load to the helium tank was reduced to below 0.8 mW in the FM from 1.2 mW in the EM. Therefore, the lifetime of the superfluid helium is more than 3 years with 30 L of liquid helium.In this paper, the thermal design and thermal test results are described.     

Cryogenic optical performance of the ASTRO-F SiC telescope

The lightweight cryogenic telescope on board the Japanese infrared astronomical satellite, ASTRO-F, which is scheduled to be launched early in 2006, forms an F/6 Ritchey-Chretien system with a primary mirror of 710 mm in diameter. The mirrors of the ASTRO-F telescope are made of sandwich-type silicon carbide (SiC) material, comprising a porous core and a chemical-vapor-deposited coat of SiC on the surface. To estimate the optical performance of the flight model telescope, the telescope assembly was tested at cryogenic temperatures, the total wavefront errors of which were measured by an interferometer from outside a liquid-helium chamber. As a result, the wavefront error obtained at 9 K shows that the imaging performance of the ASTRO-F telescope is diffraction limited at a wavelength of 6.2 microm, which is a little worse than our original goal of diffraction-limited performance at 5.0 microm.     

双膜法水处理技术的优化与改进

以冶金工业废水作为水源,将粉末活性炭和石灰乳联合投加,应用于反渗透的预处理系统,降低了超滤产水的COD,暂时硬度,高价离子含量等,有效地延长了反渗透的运行周期;采用澄清池+无阀滤池+压力式超滤+反渗透的水处理工艺技术组合,降低了设备的一次性投资及运行过程的动能费用。     

Some improvements of the performance of turbo-molecular pumps

To improve the performance of a vacuum pump means are required to increase the pumping speed and to reduce the final pressure the pump can attain.     

大口径望远镜三镜结构设计及优化

第三反射镜(简称三镜)在大口径地基光电望远镜系统中作为关键部件之一,其面形精度直接影响着望远镜光学系统成像质量.为准确设计出符合工程实际的三镜结构,从三镜镜体几何尺寸、镜坯材料、轻量化孔结构形式、支撑方式等方面进行分析,并借助于有限元工程分析软件ANSYS,MSC.Patran/Nastran对三镜的支撑点位置、支撑孔壁厚度、镜面面板厚度、镜子外边框厚度、背部肋板厚度以及镜子外边缘倒角尺寸等镜体结构参数进行优化分析,得到了使镜面面形最优的镜体各结构参数.优化后三镜镜面变形RMS值为8.98 nm、PV值为38.03 nm,均满足光学设计要求.研究成果可为同类光机系统设计提供参考.     

Optical performance of the 6.5-m off-axis new planetary telescope

We describe an off-axis design for a 6.5-m astronomical telescope optimized for low scattered light and low emissivity. This is part of a new concept for an instrument that we call the New Planetary Telescope. We show how the geometric optical performance can equal that of an on-axis conventional telescope while the diffractive performance fundamentally surpasses conventional telescopes because of the absence of pupil obstruction. The decentered concept also allows wide-field and versatile instrumentation configurations that are not possible with more-conventional designs.     

Prolonged exposure to glare and driving time: effects on performance in a driving simulator.

Twelve experienced truck drivers drove a fixed-base driving simulator for two 8 h sessions, including: (1) no glare and (2) intermittent glare presented in the exterior rear-view mirrors to simulate headlights from following vehicles. The driving task combined vehicle control on straight and curved road segments with detection of pedestrians appearing alongside the road and targets appearing in the rear-view mirrors. The results provided no evidence to support the hypothesis that prolonged exposure to glare impairs driving performance. However, we found time-related changes in target-detection and critical tracking performance, some of which were consistent with established patterns of diurnal variation. Subjective sleepiness ratings also increased over time. The results were interpreted within a model according to which drivers are able to maintain effective performance at early levels of impairment, thus compensating for increasing feelings of subjective tiredness.     

Development of mechanical cryocoolers for the cooling system of the Soft X-ray Spectrometer onboard Astro-H

Astro-H is the Japanese X-ray astronomy satellite planned for launch in 2014. The Soft X-ray Spectrometer (SXS) onboard Astro-H, is a high energy resolution spectrometer utilizing an X-ray micro-calorimeter array, which is operated at 50 mK by the ADR with the 30-L superfluid liquid helium (LHe). The mechanical cryocoolers, 4 K-class Joule Thomson (JT) cooler and 20 K-class double-staged Stirling (2ST) cooler are key components to achieve a LHe lifetime for over 3 years in orbit (5 years as a goal). Based on the existing cryocoolers onboard Akari (2006) and JEM/SMILES (2009), modifications for higher cooling power and reliability had been investigated. In the present development phase, the Engineering Models (EMs) of these upgraded cryocoolers are fabricated to carry out verification tests for cooling performance, mechanical performance and lifetime. Nominal cooling power of 200 mW at 20 K for the 2ST cooler and 40 mW at 4.5 K for the JT cooler were demonstrated with temperature and power margin. Mechanical performance test for the 2ST cooler units proves tolerability for pyro shock and vibration environment of the Astro-H criteria. Continuous running of the 4 K-class JT cooler combined with the 2ST precooler for lifetime test has achieved over 5000 h without any degradation of cooling performance.     

Porous plug and superfluid helium film flow suppressor for the soft X-ray spectrometer onboard Astro-H

Suppression of superfluid helium flow is critical for the Soft X-ray Spectrometer (SXS) onboard Astro-H, to achieve a life time of the liquid helium over 5 years. The superfluid film flow must be sufficiently small, compared to a nominal helium gas flow rate of the SXS . For this purpose, four devices composed of a porous plug, an orifice, a heat exchanger, and knife edge devices will be employed based on the experience of the X-ray microcalorimeter (XRS for X-Ray Spectrometer) onboard Suzaku. The porous plug is a phase separator of the liquid and gas helium. A potential film flow leaking from the porous plug is suppressed by the orifice. Almost all the remaining film flow evaporates at the heat exchanger. The knife edge devices stop the remaining film flow by using atomically sharp edges. In this paper, we describe the principle and design of these four devices.     

Instrumentation and performance modelling of heavy vehicle simulator tests

Flexible test road structures have been built and tested in accelerated pavement tests using a heavy vehicle simulator (HVS) at VTI in Sweden for 15 years. The objectives have been to investigate pavement responses and pavement performance behaviour, which can be used to validate mechanistic performance schemes. Here, the instrumentation is described, its accuracy is estimated, the response and performance are modelled and a performance prediction is carried out. The registrations of the measurements were rather smooth with acceptable variation. In general, good agreement was established between the measurements and calculations. The HVS machine can be used to evaluate new road concepts and maintenance strategies and provides the option of performing a life cycle cost analysis, which can decrease both costs and environmental impacts.     

Processing and performance improvements of SWNT paper reinforced PEEK nanocomposites

In this letter, the sandwich-like single-walled carbon nanotube (SWNT) paper/polyetheretherketone (PEEK) composites were successfully prepared by using a hot-compress method. Based on SEM observation, it was found that the PEEK macromolecules could diffuse into the voids of SWNT paper and were able to form very good bonding to the nanotube bundles, which ensure effective stress transfer between two phases. Some typical problems in preparing conventional carbon nanotube/polymer composites, e.g. the difficulty to obtain well-dispersed high-loading nanotubes into polymer matrices, were successfully overcome. Moreover, the compact networks of SWNTs were not destroyed at the appropriate processing condition. Correspondingly, the resulting composite (with one layer of SWNT paper) exhibited about 40% increased in Young’s modulus and 4% enhanced in failure strength when comparing with that of neat PEEK, respectively. According to rule-of-mixtures of the special sandwich-like structure, the estimated Young’s modulus can reach up to about 8 GPa, which was nearly three times of that of neat matrix. Moreover, the surface electric conductivity and thermal conductivity of the PEEK films were also increased after the addition of SWNT paper. The preliminary results suggest that the SWNT paper has great potential for being used to reinforce polymers.     

Generalization of the Zgoubi method for ray-tracing to include electric fields

The ray-tracing and spin tracking code Zgoubi, originally dedicated to the numerical integration of Lorentz equation in magnetic fields, has been improved in order to allow ray-tracing in electric and electromagnetic fields. This report describes the method, and presents detailed examples of application, including the achromatic quadrupole.     

Fine-error-sensor camera designs and performance for the Lyman Far Ultraviolet Spectrographic Explorer telescope

The Lyman Far Ultraviolet Spectrographic Explorer telescope is a glancing-incidence type with a highly curved focal surface. Because the instrument is required to guide on stars in the visible range fainter than m(v) = 16 over at least a 10-arcmin field, it is necessary to reimage the field to one, which is sufficiently flat and of appropriate scale for registration by a CCD. We present two camera designs that satisfy this requirement and discuss their overall performance.     

A simulator study of the effects of singing on driving performance

This study aimed to investigate how singing while driving affects driver performance. Twenty-one participants completed three trials of a simulated drive concurrently while performing a peripheral detection task (PDT); each trial was conducted either without music, with participants listening to music, or with participants singing along to music. It was hypothesised that driving performance and PDT response times would be impaired, and that driver subjective workload ratings would be higher, when participants were singing to music compared to when there was no music or when participants were listening to music. As expected, singing while driving was rated as more mentally demanding, and resulted in slower and more variable speeds, than driving without music. Listening to music was associated with the slowest speeds overall, and fewer lane excursions than the no music condition. Interestingly, both music conditions were associated with slower speed-adjusted PDT response times and significantly less deviation within the lane than was driving without music. Collectively, results suggest that singing while driving alters driving performance and impairs hazard perception while at the same time increasing subjective mental workload. However, singing while driving does not appear to affect driving performance more than simply listening to music. Further, drivers’ efforts to compensate for the increased mental workload associated with singing and listening to music by slowing down appear to be insufficient, as evidenced by relative increases in PDT response times in these two conditions compared to baseline.     

Development of porous plug phase separator and superfluid film flow suppression system for the Soft X-ray Spectrometer onboard ASTRO-H

ASTRO-H is the sixth Japanese astronomy satellite scheduled for launch in 2014. The Soft X-ray Spectrometer instrument is onboard ASTRO-H. This is a 6 × 6 array of X-ray microcalorimeters with an energy resolution of <7 eV at 0.5–10 keV. Superfluid liquid helium is utilized as a part of the cooling system. To retain the liquid helium in the tank under zero-gravity, a porous plug phase separator made of sintered stainless is used. Since the vapor mass flow rate is only 29 μg/s, any additional superfluid film loss influences the lifetime of the liquid helium. Therefore, a film flow suppression system consisting of an orifice, a heat exchanger, and knife edge devices is adopted based on the design used for the X-ray Spectrometer onboard Suzaku. The film flow will be suppressed to <2 μg/s, sufficiently smaller than the vapor flow rate. In the present investigation, the design and ground experiments of a helium vent system composed of the porous plug and film flow suppression system are presented. The results show that the phase separation and the film flow suppression are satisfactorily achieved.     

新型X射线管的研制与性能测试

普遍应用于工业探伤的无损检测设备-X射线探伤机．其核心部分是X射线管。本文设计制作了一种新型结构的X射线管。其阳极采用“大靶”并装有热管，根本上解决散热问题．同时使用无油超高真空排气技术．提高了管内真空度从而改进其性能。使探伤机的连续工作时间与效率提高了一倍。