摘要:

The paper describes a cathode-ray tube in which the scanning and light generating functions are separated by a large-area electron multiplier. The multiplier is scanned by a low-voltage, low-current electron beam. The amplified electron output from the multiplier is accelerated to the fluorescent screen to produce a bright display. Suitable electron multipliers have been made and tested in a specially designed magnetically scanned CRT. The approach allows much more freedom in cathode-ray tube design and some examples of the advantages to be gained are described.

DOI:10.1049/ip-i-1.1984.0002

出版商:IEE    

年代:1984

数据来源: IET

摘要:

Large-area electron multipliers have been made which have operated successfully in CRTs. These multipliers consist of a stack of perforated metal dynodes separated by insulators. The aspects of multiplier performance which are important for use in CRTs are the gain and its uniformity, the maximum output current available and the spatial resolution. The multipliers have a uniform, high gain and can provide an output current of more than 1.5 mA per channel. The spatial resolution is determined by the technology of multiplier construction which is based on dynodes whose manufacture is closely related to that of delta shadow masks.

DOI:10.1049/ip-i-1.1984.0003

出版商:IEE    

年代:1984

数据来源: IET

摘要:

It has been established that large-area channel electron multipliers can be used in cathode-ray tubes to separate the scanning and light generating functions within the tube. The resulting low-voltage scanning beam can be utilised to make a thin deflection system. The paper describes the mode of operation of this deflection system, accompanied by photographs which illustrate the performance. Brief mention will also be made of plans to make sealed-off tubes with a 12 in picture diagonal that will be 75 mm thick and have a power consumption of about 5 W.

DOI:10.1049/ip-i-1.1984.0004

出版商:IEE    

年代:1984

数据来源: IET

摘要:

In the channel-plate CRT, the problems of colour selection are entirely different from those in conventional CRTs because of the separation of addressing and light generation. Three methods of achieving colour selection are at present being investigated. The ‘dots-and-rings’ method uses the property that the shape of the beams emerging from the channels is annular and controlled by the output electric field. An electrode system has been developed to direct the output electrons onto one of three colours, deposited on the screen as an array of dots, each surrounded by two rings. With the second method, the electrons emerging from the channels are focused into lines which can be deflected onto an array of phosphor stripes in the three colours. Colour selection can also be achieved using penetron screens. The channel-multiplier CRT has the advantage over conventional penetron tubes that deflection sensitivity does not change with colour.

DOI:10.1049/ip-i-1.1984.0005

出版商:IEE    

年代:1984

数据来源: IET

摘要:

A new concept for treating the effects of dust on the electrical performance of photovoltaic concentrators is presented in the paper. The dust concentration in the atmospheric air around the concentrator is measured continuously during the test period. The rate of dust accumulation on the concentrator surface is determined. The concentrator performance degradation, as a result of dust accumulation, is related to the amount of dust accumulated per unit area of the collector surface (in g/m2) rather than the exposure time. It has been shown that major reductions in the short-circuit current and the efficiency are observed for dust accumulations up to 5.4 g/m2. The accumulation of dust on the photovoltaic concentrator causes a successively larger ‘rounding’ of theI/Vcharacteristic at constant incident direct normal radiation intensity and constant cell temperature. This effect is equivalent to an increase in the internal series resistance of the concentrator. This dust-equivalent series resistance increases with increasing dust accumulation.

DOI:10.1049/ip-i-1.1984.0006

出版商:IEE    

年代:1984

数据来源: IET

摘要:

Experimental results on self-sustained oscillations in (GaAl) As double-heterostructure injection lasers are presented. A comparison is made between the emission properties of shallow proton bombarded stripe-geometry lasers with those of oxide-insulated stripe-contact lasers. The rate of increase of oscillation frequencies with injection current or output power is found to be greater for oxide-insulated lasers. Carrier density profiles are obtained from the spontaneous emission at short wavelength from the front facet, as well as from the luminescence through a window (open-back) in the substrate cladding. A model for narrow-stripe lasers has been used, which considers current spreading under the stripe by dividing the laser into three regions in the lateral plane. It is found experimentally that the width of the regions outside the stripe should be of the order of the stripe width, and the regions beyond these may be treated as optically absorbing, with an absorption factor γ of 0.06.

DOI:10.1049/ip-i-1.1984.0007

出版商:IEE    

年代:1984

数据来源: IET

摘要:

X-band Impatt diodes are frequency modulated by optical illumination. The light is coupled through a standard optical fibre to the diode oscillating in a waveguide resonant circuit. Direct modulation of a semiconductor laser is used for the frequency modulation. A maximum modulation frequency of 2.5 MHz can be obtained.

DOI:10.1049/ip-i-1.1984.0008

出版商:IEE    

年代:1984

数据来源: IET

摘要:

Experimental results of two kinds of optical effects, optical tuning and optical switching, of GaAs MESFET oscillators are presented. For optical tuning, the oscillation frequency decreases with optical illumination and the maximum tuning range depends principally on oscillator mode (common-source, common-drain or common-gate), with 3.8% and 1.9% being achieved at S band and X band, respectively, with an optical power density of 0.5 mW/mm2. The oscillator power output generally increases with optical illumination, the increase being around 1 to 2 dB at 0.5 mW/mm2light intensity. For optical switching, power output switching from no oscillation to 7.5 mW was obtained at X band with illumination from a 2 mW laser diode. The optical response of microwave GaAs MESFET oscillators is attributed to the capture of holes by two kinds of hole traps in the Schottky-gate depletion region. The oscillation frequency and power output changes with optical illumination become appreciably reduced with increase of optical modulation rate, becoming 10% of the constant-illumination induced change at an optical modulation rate of 1 MHz and negligibly small at 10 MHz. The drain current bias still responds above 10 MHz, with a response amount about 0.5 mA attributed to the photoconductivity effect in the channel.

DOI:10.1049/ip-i-1.1984.0009

出版商:IEE    

年代:1984

数据来源: IET

DOI:10.1049/ip-i-1.1984.0010

出版商:IEE    

年代:1984

数据来源: IET