Channel Multiplier Instrumentation for the Measurement of Low-Energy Auroral Particles

Channel multiplier instruments have been developed and used to measure the low-energy electron and proton auroral fluxes from a polar-orbiting satellite. Seven channel multipliers preceded by individual 90° magnetic analyzers were used to measure the differential electron energy spectrum. The central energies of the analyzers were 1.1, 2.1, 5.3, 14, 31, and 76 keV; the seventh channel was designed to be a background monitor. The integral proton number spectrum was measured using four channel multiplier threshold counters. Proton thresholds, determined by nickel foils, were chosen to be 21, 38, 56, and 1000 keV. A broom magnet was used to sweep out low-energy electrons. The saturated output pulses from each channel multiplier were amplified and fed into a logarithmic ratemeter. The in-flight operation of the instruments was monitored with low-level radioactive sources. The ratemeter calibration was independently monitored using a programmed pulser which was activated by ground command. Data obtained from these instruments during a three-day period in November, 1965, will be presented. Improved versions of these instruments, described herein, have been designed and tested for future flights.     

Instrumentation for Monitoring Current from a 30 MeV Electron Linac

Non-intercepting monitors for measuring the total current or charge passing down the electron drift tubes have been constructed which are suitable for electron pulses from about 50 nanoseconds to 3.5 microseconds in width. Measurements are derived from output signals which are tuned to frequencies in the range 250 kcs to 45 kcs. Alternatively, for viewing pulse envelopes, ferrite coil outputs are integrated by a 25 ohm termination. The monitors are calibrated using an air cooled Faraday cup which is described.     

单晶硅表面钝化层在低能电子辐照前后的SIMS和XPS分析

为了研究低能电子辐照对单晶硅器件表面钝化材料中产生的化学微结构的变化,在轻掺杂P型单晶硅基底上制作了三种表面钝化膜,分别是单一SiO₂钝化膜、SiO₂/Si₃N₄复合钝化膜、硼硅玻璃/Si₃N₄复合钝化膜,开展了表面钝化单晶硅在最大能量70 keV的加速器电子束下的辐照实验。样品在空气气氛下辐照6 h,用二次离子质谱(SIMS)测试了辐照前后三种表面钝化膜中Si、N、B的纵深变化,同时用Ar离子刻蚀X射线表面光电子能谱(XPS)对Si元素的化学结合状态进行测试分析。结果表明:对单一SiO₂钝化的轻掺杂P型材料,辐照在SiO₂/Si界面产生明显的材料结构变化,界面附近的SiO₂不再是完整化学计量比,而是SiO_x(x<2);对SiO₂/Si₃N₄复合钝化的轻掺杂P型材料,辐照对SiO₂     

A Magnetic Electron Analyzer for Plasma Focus Electron Energy Distribution Studies

The paper describes the construction of a magnetic electron analyzer for pulsed beam electron energy distribution studies. The single shot information is obtained using a NMOS linear image sensor. Both the energetical and the sensitivity calibration were performed using careful numerical simulations. For simplicity, the signals can be read on an oscilloscope, and they are transmitted via an optic fiber, which allows the analyzer to work while connected to high voltage. The analyzer was successfully implemented on a 15 kV/3 kJ plasma focus device and was used to study the electron energy distribution in the 30–660 keV range..     

Multi-Wire Proportional Counters for Low-Energy Particles

We have constructed multi-wire proportional-counter arrays in which only every second wire operates as an anode, the others being held at the cathode potential, and have investigated their response to a particles. The variation of the sensitivity and amplification with voltage and with different geometrical arrangements is described.     

A High Performance 4500 Volt Electron Multiplier Bias Supply for Satellite Use

A tuned-secondary sinewave oscillator combined with a Cockcroft-Walton voltage multiplier has been developed which produces 40 ?A at 4500 volts from 12 VDC with 80% efficiency. Optimum efficiency is obtained by considering the Cockcroft-Walton multiplier as part of the oscillator design. Equations are developed for calculating the multiplier output voltage and ripple as a function of the oscillator output frequency and amplitude, the capacitance of the multiplier, the number of multiplier stages, and the load current. The Atmosphere Explorer Photoelectron Spectrometer electron multiplier bias supply is also described to illustrate practical design tradeoffs and techniques employed when the supply is used in a satellite-borne particle detection experiment.     

Studies on Mutation Breeding of High-Yielding Xylanase Strains by Low-Energy Ion Beam Implantation

As a new mutagenetic method, low-energy ion implantation has been used widely in many research areas in recent years. In order to obtain some industrial strains with high xylanase yield, the wild type strain Aspergillus niger A3 was mutated by means of nitrogen ions implantation （10 keV, 2.6× 10^14 ～ 1.56 × 10^15 ions/cm^2） and a mutant N212 was isolated subsequently. However, it was found that the initial screening means of the high-yielding xylanase strains such as transparent halos was unfit for first screening. Compared with that of the wild type strain, xylanase production of the mutant N212 was increased from 320 IU/ml to 610 IU/ml, and the optimum fermentation temperature was increased from 28 ℃ to 30 ℃.     

Electronics and Instrumentation for NMR Imaging

The development of Nuclear Magnetic Resonance (NMR) imaging has brought together the experimental techniques of NMR spectroscopy and image processing with the consequence that new experimental requirements and apparatus are currently being developed. Examples of these requirements include the large amounts of data which can be generated and the effect on data processing and storage requirements. Also, the increased size of objects under investigation necessitate some major changes in the magnet and r.f. system. A discussion of these specific requirements is presented together with an overview of all components of the NMR imaging system.     

Electron Temperature Measurement Using PIN Diodes as Detectors to Record the X-ray Pulses from a Low-Energy Mather-Type Plasma Focus

In the experiment to determine the plasma electron temperature, a modified multichannel PIN diodes assembly is used as detectors to record the X-ray pulses from a low-energy Mather-type plasma focus device energized by a 32μF, 15 kV (3.6 k J) single capacitor, with deuterium as a filling gas. The ratio of the integrated bremsstrahlung emission transmitting through foils to the total incident flux as a function of foil thickness at various temperatures is obtained for foil absorbers of material. Using 3μm, 6μm, 9μm,12μm,15μm and 18μm thick aluminium absorbers, the transmitted X-ray flux is detected. By comparing the experimental and theoretical curves through a computer program, the plasma electron temperature is determined. Results show that the deuterium focus plasma electron temperature is about 800 eV.     

环境气溶胶的核孔膜、扫描电子显微镜和微电子探针研究

用云母核孔膜、扫描电子显微镜和微电子探针对工艺房间空气中悬浮的气溶胶进行了采集 ,并对气溶胶的粒径分布、微粒形态及结构、元素成分和捕集机制进行了研究。     

新型低能辐射远程测量系统设计

为了实现低能辐射精确的远程测量,设计了一种基于ARM单片机和ZigBee无线传输的新型低能辐射远程测量系统,优化了前端算法,提出了精度更高的整体求和算法。系统可靠性利用ARM单片机发射数据与ZigBee接收数据的一致程度来测试,算法精确度利用MATLAB进行图像处理,再计算辐射亮点灰度值,并用插值拟合方法进行数据处理来测试。实验结果表明,整体求和算法的运用以及ARM和ZigBee的结合可实现低能辐射精确的远程测量。     

Instrumentation and Controls for the Stanford Linear Accelerator

We discuss the philosophy of an accelerator instrumentation system, and techniques which have been worked out for handling the various remote sensory and control functions required for proper operation of the accelerator. Lack of time prohibits more than incidental reference to philosophy of operation of the machine.     

Improved Instrumentation for Stack Gas Monitoring

A microprocessor-based stack gas monitoring instrument designed to overcome certain limitations associated with conventional methods of stack monitoring is described. Emphasis during the instrument's development has been placed on simplicity, reliability and low cost, while obtaining more useful information for proper stack gas monitoring.     

低能加速器开关电源研制

利用直流脉宽调制技术以及半桥变换电路,为一种低能电子直线加速器成功研制阳极开关电源。根据开关电源的特点,对该电源中低压和高压部分进行详细设计。低压部分采用SG1525A为控制核心,实现脉宽调制、软启动、稳压调节以及过压保护功能。该开关电源主要指标:输出电压0~800V,最大电流400 m A,工作频率为18.5 k Hz,纹波峰值系数为0.9‰,达到设计要求。     

强流栅控电子枪设计分析

电子枪是超高真空电子器件,可用于各类加速器的束流源与功率源中,是加速器与微波电子管的主要与关键部件之一.结合某辐照加速器电子枪实际需要,对其束流光学系统进行了计算机模拟和优化设计.模拟结果表明该电子枪在80 kv高压下工作时,输出电流可以达到5 A以上,束流发射度、枪区电场以及束腰半径可以满足该加速器运行的需要.电子枪...     

Dedicated Eprom-Based Computer for Distributed Instrumentation Control

The LLNL Nuclear Chemistry Counting Facility (NCCF) is being converted to a modern production facility. A computer network has been designed and built to implement this conversion. The outermost node of the computer network is a dedicated EPROM-based controller. Tne controller handles the details of driving the attached nuclear instrumentation, providing a standard interface to the remainder of the network. This paper addresses the design and the implementation of the dedicated instrunientation controller.