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The reviews and prospects for radiometer calibration research of BIRMM (Beijing Radio Institute of Metrology and Measurement) are presented in this paper. The paper's interests are concentrated on three principal parts as follows. Firstly, the timetable about research for radiometer calibration target is shown in a figure according to time sequence since 1995. Second, the traceability link for calibration targets, including their operational theory, is introduced in the section III and section IV concisely. Finally, the discussion about two key points of radiometer calibration and summary based on content above are presented in the end.

Summary form only given. The characterization of microplasmas driven by DC and AC (50~1000 Hz) power supplies with a voltage up to 1000 V at atmospheric pressure is performed. Parallel planar aluminum electrodes with an inter-electrode gap 20~200 mm are patterned on a glass substrate by semiconductor fabrication processes. Pure argon and helium are used as the feedstock. Filamentary-like discharges are mostly observed in argon discharges and highly-nonuniform discharges result in locally high current densities, which lead to a severe damage of the electrode. In helium discharges, a corona-like discharge is observed when the plasma is ignited with the applied voltage slightly higher than the breakdown voltage. Under certain conditions, such discharges occupy the entire inter-electrode space. With the increase in the applied voltage, the transition to filamentary-like discharges is occurred. It is shown that the breakdown voltage increases with the gap, and the voltage is 100-200 V higher than that shown in the right branch of the Paschen curve. Oscillations of current and voltage waveforms at different frequencies are observed after the plasma is ignited. Preliminary studies show that the MHz-high frequency oscillation is associated with the external circuits due to the sudden voltage drop after the breakdown. The low frequency oscillation, few tens of kHz, is a result of the repetitive ignition and extinguishment of the discharge. No stable discharge is obtained. Such a behavior is seen in both DC-and AC-driven discharges. P-spice circuit simulation is performed to study the effects of the external circuitry on the discharge behavior. The I-V characteristics are simulated, and results qualitatively agree with the experimental measurements. The optical emission emanating from the plasma is monitored and the broadening of hydrogen emission lines is used to estimate the plasma characteristics, namely the electron density and neutral gas temperature. Finally, the potential using such a discharge in materials processing will be demonstrated.

The characterization of the downstream of an oxygen atmospheric pressure plasma jet (APPJ) is performed. This APPJ is sustained by pulsed power with a repetitive frequency up to 25 kHz. The reactivity of the plasma at different operating conditions is characterized using the intensities of O 2 (759 nm) and O (777 nm) optical emission lines. The jet downstream temperature is measured by a thermocouple. It is shown that the intensity of O 2 emission is not sensitive to the flow rate while it increases with the increase in the applied voltage. O emission is only observed at high flow rate. The temperature measurement shows that it slightly increases with the applied voltage. At the jet exit, the temperature monotonically increases with the flow rate while at 1 cm downstream of the jet, it shows an opposite trend. It is shown that the existence of an external surface at the downstream greatly influences the emission spectra adjacent to the surface. When the jet downstream is shielded with a glass tube, the O radical emission intensity increases by more than one order of magnitude. Preliminary studies show that the presence of the surface potentially enhances certain surface reactions. Such an enhancement leads to the increase of the O radical density, as suggested by the spatial-resolved optical emission spectra.

The growth mechanism of ZnO thin films deposited by an atmospheric pressure plasma jet (APPJ) is study. The APPJ used is sustained by a pulsed power source with a repetitive frequency up to 25 kHz using N 2 or O 2 as plasma gases. Nebulized zinc chloride solution is used as the precursor and is sprayed into the downstream of the plasma jet to deposit thin films on Si wafers. X-ray diffraction spectra show that the crystalline structure changes with the operating parameters, namely plasma gas flow rate and the applied voltage, which influence the jet temperature and reactivity. It is found that upon exposure of the precursor to the plasma jet, sheet-like zinc hydroxide chloride (ZHC) are formed first, and is converted to zinc oxide if the jet temperature is high enough. Under relatively low temperature, the conversion of the precursor end at ZHC. The grain size of the films is greatly influenced by the nucleation and growth rate. High jet temperature leads to a larger number of the nuclei and results in smaller grain sizes and denser ZnO thin films. O 2 plasma jets are also utilized. Preliminary studies show that the O 2 plasma jet is able to convert the precursor to ZnO thin films under optimized conditions. Finally, the key parameters that influence the electrical and optical properties will be identified.

this paper presents the results of a twelve month Broadband over Powerline (BPL) in-building trial in a Multi-Dwelling Unit (MDU) environment utilizing the building's low voltage electric distribution wiring for the BPL system transport medium to support an IP Closed Circuit Television (CCTV) and VoIP Intercom application. Specifically, the BPL infrastructure for this trial was designed to provide high speed bi-directional data communications in support of voice and video security applications for a sixteen story residential building with over one hundred apartments. The BPL system has been extensively monitored during the trial over a five month period with a network management system and has been highly stable, indicating a viable network solution using this technology for broadband applications such as CCTV and Intercom. In contrast to traditional CAT-5E cabling, this system had a much shorter implementation time along with up to 50% cost savings.

This paper presents the results of a large scale field trial conducted over a period of 18+ months for a broadband over powerline communications system in a medium voltage overhead distribution network. Specifically, this infrastructure was designed to provide high speed bi-directional communications for electric utility devices in an intelligent grid environment supporting voltage and current sensors, remote controlled pole top switches and electric meter collection devices, among others.

p/sup ++/-GaAs/n-InGaP heterojunction field-effect transistors (HJFETs) with a highly carbon-doped gate and a wide-gap channel were reported. A self-aligned T-shaped gate HJFET exhibits a gate of 0.6 /spl mu/m in length by depositing gate metal of 1.0 /spl mu/m. DC characteristics including a turn-on voltage of 2.0 V at 1 mA/mm, a gate-drain breakdown voltage up to 30 V, a drain-source breakdown voltage exceeding 25 V, a maximum available transconductance of 160 mS/mm and AC performances such as a unit-current gain frequency of 16.8 GHz, and a unit-power gain frequency of 25 GHz were obtained for a non self-aligned HJFET. With a self-aligned processing structure, the transconductance and f/sub max/ were improved to 230 mS/mm and 35 GHz, respectively.

InGaP/InGaAs pseudomorphic high electron mobility transistors (PHEMTs) fabricated using single-gate and dual-gate methodologies have been characterized with special emphasis to precisely control the device linearity and the gate-voltage swing. The key features of the proposed PHEMT profile are characterized in a composite channel by using a GaAs delta sheet and an undoped InGaAs layer. The gate voltage dependence of transconductance for the first equivalent gate with several V/sub gs2/ shows that the gate voltage swing available is in the range of 0 to 4.5 V.

Summary form only given. Continuous-wave GaAs mushroom structure surface emitting laser (MSEL) operation at a threshold current as low as 1.6 mA, an output power >2.0 mW, and a single transverse mode up to three times threshold current is reported. The relatively large CW output power was achieved by reducing the series resistance using a selective zinc diffusion. The low threshold current and single-mode operation are attributed to good lateral current confinement in a small constricted region formed by mesa undercutting. The complete device was mounted junction-side up on a chip carrier and tested CW at room temperature. Some results are given. >