Beam buncher for the K130-cyclotron

A beam buncher, developed to improve the beam efficiency in the K130 cyclotron at University of Jyväskylä, is described. The basic acceleration frequency and the second harmonic component were used to simulate a saw-tooth wave, needed for axial injection of the beam. With this method up to eight times increase in the beam intensity was achieved.     

LLRF systems for subharmonic buncher system of BEPCII Linac

The linear accelerator (Linac) completed in 2007 for the upgrading project of the Beijing Electron Positron Collider (BEPCII) provides 1.89 GeV electrons and positrons for the storage rings. BEPCII Linac decides to update the bunching system and adopts two-bunch operation to enhance beam quality and injection rate as its second update phase. Two subharmonic bunchers will be used in this project: one operates at 142.8 MHz and the other operates at 571.2 MHz. Each subharmonic buncher consists of the bunching cavity, power source, LLRF system and other related subsystems. This paper mainly describes the LLRF systems for the subharmonic buncher systems (SHB).     

Large permanent magnet quadrupoles for an electron storage ring

We have built large high quality permanent magnet quadrupoles for use as interaction region quadrupoles in the Cornell Electron Storage Ring where they must operate in the 10 kG axial field of the CLEO experimental detector. We describe the construction and the magnetic measurement and tuning procedures used to achieve the required field quality and stability.     

3D numerical model of electromagnetic quadrupoles for the GrenobleEuropean Synchrotron

The magnetic flux density B (B_x≈0, B_y, B_z≈0) produced by the quadrupole magnets of the future Grenoble European Synchrotron is computed. This value is needed to obtain the focusing force acting on the electrons. The finite-element software package FLUX3D is used to compute the flux density B and other useful parameters. A second-order tetrahedral mesh and a reduced scalar potential formulation have been chosen to solve this problem, taking into account the inducing coils, with accurate results in nonferromagnetic materials     

maXs: Microcalorimeter Arrays for High-Resolution X-Ray Spectroscopy at GSI/FAIR

Highly-charged heavy ions like U⁹¹⁺ provide unique conditions for the investigation of relativistic and quantum electrodynamical effects in strong electromagnetic fields. We present two X-ray detectors developed for high-resolution spectroscopy on highly-charged heavy ions. Both detectors consist of metallic magnetic calorimeters (MMCs) forming linear eight-pixel arrays. The first detector, maXs-20, is developed for the detection of X-rays up to 20?keV with an energy resolution below 3?eV. The second device, maXs-200, is designed for X-ray energies up to 200?keV with an energy resolution of 40?eV. The results of characterization measurements of single detectors of both arrays will be shown and discussed. In both cases, the performance of the detectors agrees well with their design values. Furthermore, we present a prototype MMC for soft X-rays with improved magnetic flux coupling. In first characterization measurements the energy resolution of this device was 2.0?eV (FWHM) for X-rays up to 6?keV.     

Super high resolution for long-range imaging

A new optical system with a resolution that is superior to the resolution of the usual optical systems with diffraction limit is presented. We introduce a newly generated narrow light beam that propagates for a long range while almost maintaining its beam width and show that the beam width is narrower than that of the diffraction limit of normal optics. Thus a super high resolution is achieved for a long range, e.g., a range of a few kilometers, by the use of a 10-cm-diameter telescope. The high resolution for long-range imaging can be obtained by a Galilean telescope with a negative eyepiece that has a spherical aberration. We demonstrate theoretically high-resolution imaging by using simple objects and assuming a telescope 10 cm in diameter and a visible wavelength. A comparison of simulation results by the conventional optical system and by the special optical system clearly shows the superiority of the new system.     

PTCR陶瓷材料的超低温烧结

主要研究了ＢＮ对ＰＴＣＲ陶瓷材料低温烧结的作用．对Ｌａ掺杂ＢａＴｉＯ_３ＰＴＣＲ陶瓷,在１１００℃的低温下烧结可以得到室温电阻率为１５０Ω·ｃｍ、升阻比为４．９个数量级的样品．对居里温度为３６０℃的高居里点（Ｂａ_０．４Ｐｂ_０．６）ＴｉＯ_３ ＰＴＣＲ陶瓷材料,选用 Ｎｂ_２Ｏ_５为半导化剂,ＢＮ和ＡＳＴ为助烧剂时,可以在１０００℃左右的超低温下烧成．同时,对ＢＮ助烧剂的液相烧结机制进行了初步的探讨．     

某超高层建筑电气设计实例

本文结合新近完成的超高层工程实例,提出了超高层建筑电气设计的特殊关注点,并就配电方案、供电可靠性、设计管理、节能等问题给出了解决方案.     

两种超分辨ISAR成象算法

为提高逆合成孔雷达（ＩＳＡＲ）图象的分辨率,本文介绍了连续Ｈｏｐｆｉｅｌｄ神经网络和ＥＳＰＲＩＴ两种超分辨技术。通过对实验ＩＳＡＲ回波数据的处理表明,与常规的ＦＦＴ算法以及普通超分辨成象算法相比较,这两种新算法明显地提高了图象分辨率。     

Monte Carlo simulations for the shielding of the future high-intensity accelerator facility FAIR at GSI

The Gesellschaft für Schwerionenforschung (GSI) is planning a significant expansion of its accelerator facilities. Compared to the present GSI facility, a factor of 100 in primary beam intensities and up to a factor of 10,000 in secondary radioactive beam intensities are key technical goals of the proposal. The second branch of the so-called Facility for Antiproton and Ion Research (FAIR) is the production of antiprotons and their storage in rings and traps. The facility will provide beam energies a factor of approximately 15 higher than presently available at the GSI for all ions, from protons to uranium. The shielding design of the synchrotron SIS 100/300 is shown exemplarily by using Monte Carlo calculations with the FLUKA code. The experimental area serving the investigation of compressed baryonic matter is analysed in the same way. In addition, a dose comparison is made for an experimental area operated with medium energy heavy-ion beams. Here, Monte Carlo calculations are performed by using either heavy-ion primary particles or proton beams with intensities scaled by the mass number of the corresponding heavy-ion beam.     

Design of an upgradeable 45–100 mA RFQ accelerator for FAIR

A 325 MHz, 35 mA, 3 MeV Radio-Frequency Quadrupole (RFQ) accelerator will be operated as the first accelerating structure of the proton linac injector for the newly planned international science center Facility for Antiproton and Ion Research (FAIR) at GSI, Germany. In previous design studies, two high beam intensities, 70 and 100 mA, were used. Most recently, the design intensity has been changed to 45 mA, which is closer to the operational value. Taking advantage of the so-called New Four-Section Procedure, a new design, which is upgradable from 45 to 100 mA, has been developed for the FAIR proton RFQ. Besides the upgradability analyses, robustness studies of the new design to spatial displacements of the input beam and field errors are presented as well.     

Stirling Cryocooler for High-Temperature Super Conductor RF Filters

The High Temperature Super Conducting (HTSC) radio frequency (RF) filters (as used, for example, in ground base stations for cellular phone systems) are passive devices. To operate properly, they must be cooled well below their transition temperature to super conducting stage (usually to 65–80 K). These HTSC RF filters are connected through a coaxial cable to an array of Low Noise Amplifiers (LNA), which are active devices and, therefore, induce a few hundreds mWatts of heat. On the other hand, the LNA array is connected by coaxial cable to a feedthrough of the vacuum chamber. This coaxial cable also contributes a few hundreds mWatts of heat load. The third source of heat load is the thermal radiation from the vacuum jacket wall to the cryogenically cooled surfaces. This portion of heat load is assessed as hundreds of mWatts as well. The signal-to-noise ratio of LNA devices is improved significantly when they are cooled down to a temperature of 90–110 K and their effectiveness reaches 99% at a temperature of 77 K. Traditionally, cooling of the system is achieved by placing both the HTSC RF filters and the LNA array device on the cold tip of a single-stage cryogenic cooler. Hence, both devices are cooled down to a temperature of 60–80 K, which is required by the manufacturers of HTSC RF filters. Because of the high level of heat loads induced by the LNA array, this method requires an extra cooling capacity from a cryogenic cooler. This increases power consumption, weight, and size and decreases its reliability. This paper describes a method of reducing the overall heat load. This method relies on the idea of maintaining the HTSC RF filters and the LNA arrays in different operational temperatures. The objective of this method is to provide a reduction in thermal losses, input power, weight, and size and to increase the reliability of the entire cryogenic cooler. The method allow for better ruggedising of the mechanical support for cooled electronic package of the LNA array plate.     

Electromagnetic energy harvester for harvesting acoustic energy

This paper reports a suspended coil, electromagnetic acoustic energy harvester (AEH) for extracting acoustical energy. The developed AEH comprises Helmholtz resonator (HR), a wound coil bonded to a flexible membrane and a permanent magnet placed in a magnet holder. The harvester’s performance is analyzed under different sound pressure levels (SPLs) both in laboratory and in real environment. In laboratory, when connected to 50 Ω load resistance and subjected to an SPL of 100 dB, the AEH generated a peak load voltage of 198.7 mV at the resonant frequency of 319 Hz. When working under the optimum load resistance, the AEH generated an optimum load power of 789.65 µW. In real environment, the developed AEH produced a maximum voltage of 25 mV when exposed to the acoustic noise of a motorcycle and generated an optimum voltage of 60 mV when it is placed in the surroundings of a domestic electrical generator.     

超低空雷达天线底座涂装工艺

介绍了超低空雷达天线底座的涂装工艺。应用结果表明,该工艺能够满足海岸区域雷达天线底座油漆涂层的防霉,防湿热,防盐霉要求,防腐蚀期可达５年以上。     

Super Compact UWB Monopole Antenna for Small IoT Devices

This article introduces a novel, ultrawideband (UWB) planar monopole antenna printed on Roger RT/5880 substrate in a compact size for small Internet of Things (IoT) applications. The total electrical dimensions of the proposed compact UWB antenna are 0.19 λ_o × 0.215 λ_o × 0.0196 λ_o with the overall physical sizes of 15 mm × 17 mm × 1.548 mm at the lower resonance frequency of 3.8 GHz. The planar monopole antenna is fed through the linearly tapered microstrip line on a partially structured ground plane to achieve optimum impedance matching for UWB operation. The proposed compact UWB antenna has an operation bandwidth of 9.53 GHz from 3.026 GHz up to 12.556 GHz at −10 dB return loss with a fractional bandwidth (FBW) of about 122%. The numerically computed and experimentally measured results agree well in between. A detailed time-domain analysis is additionally accomplished to verify the radiation efficiency of the proposed antenna design for the ultra-wideband signal propagation. The fabricated prototype of a compact UWB antenna exhibits an omnidirectional radiation pattern with the low peak measured gain required of 2.55 dBi at 10 GHz and promising radiation efficiency of 90%. The proposed compact planar antenna has technical potential to be utilized in UWB and IoT applications.     

超高强铝合金的发展与研制开发方向

扼要地介绍了超强铝合金的发展现状,简单地论述了超强铝合金的化学成分,特性与应用领域.着重论述了超强铝合金的制备技术及研制开发的方向.     

某超高层建筑空调系统设计简介

介绍了某超高层综合楼的空调系统设计。在充分考虑该建筑自身的特点和使用要求的基础上,确定的空调方式为：制冷采用变制冷剂流量的多联分体式空调（VRF）系统,空调外机分别设置于五个不同高度的设备层外侧;而制热则采用了以集成于VRF室内机出风端的热水盘管为主要末端的水系统,按照设备承压能力要求在两个不同高度的设备分别设置了一、二级换热系统。在大型超高层建筑设计中,这种较为特殊地全部采用VRF并集成热水盘管的空调方式,值得探讨。