Rise time

About: Rise time is a research topic. Over the lifetime, 4748 publications have been published within this topic receiving 47512 citations.

Electric field step in air gap streamer discharges

Abstract: Electric field (E-field) in air gap streamer discharges under positive lightning impulse was measured by specifically developed integrated electro-optic sensors. An E-field step phenomenon was observed. The E-field firstly agreed with the Laplace field, then suddenly increased with a rise time of μs. The occurrence probability of this phenomenon increased as the applied voltage increased. The discharge current waveforms and photos taken by a fast camera prove the E-field step was caused by the space net charge. From the E-step rise time and the corona area range, the average electron drift speed under the experiment situation was estimated about 0.2 × 106 – 0.6× 106 m/s.

AlGaInP optical source integrated with fiber links and silicon avalanche photo detectors in fiber optic systems

Abstract: This study has clarified aluminium gallium indium phosphide (AlGaInP) optical source integrated with fiber links and silicon avalanche photodetectors in fiber optic systems. The output spectral power, rise time, signal frequency and resonance frequency for AlGaInP laser diode. The laser diode rise time, output spectral power and resonance/signal frequencies versus injection current and ambient temperatures are sketched. The silica doped germanium fiber link pulse broadening and the signal fiber bandwidth are investigated against temperature variations. The signal per noise ratio is related to Q value and bit error rate (BER) at the receiving point (Si avalanche photodetector (APD)) are sketched with temperature.

System and method for evaluating and calibrating a radiation generator

Abstract: A method and multipurpose apparatus that can evaluate an x-ray system performance for the purposes of quality assurance testing, servicing, optimization of technique factors and on-line x-ray source control. The apparatus offers self-consistent evaluation of kVp (Kilovolts Peak), Half Value Layers (HVL), x-ray exposure or kerma, exposure time, relative or calibrated mA, rise time, fall time, ripple factor and automatic identification of voltage or current spikes and break downs in a single x-ray exposure. This apparatus, by measuring radiation parameters from the same exposure, provides an accurate determination of parameters overcoming inconsistencies present in the traditional method of using several exposures. This apparatus uses a multiple sensor assembly with computer controlled electronics for optimization of signal conditioning and operational parameters. A filter package with varying material and thickness of x-ray attenuators in positions corresponding to sensors is used for self-consistent determination of kVp, mA, etc.

Time-resolved investigations of pulsed microwave excited plasmas

Abstract: Pulsed microwave excited (245 GHz) argon plasmas generated by a slot antenna type plasma source are investigated by various diagnostic tools Through the combined use of time-resolved planar optical emission spectroscopy (TPOES), microwave interferometry (MWI) and Langmuir probes the temporal behaviour of the electron density, ne (t ), and effective electron temperature, Te (t ), for the pulse frequency range of 02-20 kHz are measured Additionally, from TPOES maps of Ar* and Ar+ , the qualitative spatially and time-resolved electron temperature distribution is derived The ne (t ) and Te (t ) rise and decay times are almost constant throughout the examined frequency range A ne (t ) rise time of 1 ms and a decay time of 06 ms is derived from probe and MWI data at 5 Pa A Te (t ) rise time between 5 and 10 µs and a decay time between 50 µs and 80 µs is derived from TPOES and probe measurements at 5 Pa The maximum time-averaged electron density, e , at 5 Pa is obtained at a pulse frequency f of 200 Hz With increasing pressure and power the pulse frequency f at which a maximum of e is reached decreases to f 50 Hz The temporal ne (t ) and Te (t ) behaviour for the investigated pressure range is described by a simple set of equations based on the `Global Model' of pulsed plasmas It can be concluded that the electron loss rate loss controls both the rise and decay times of ne (t ) The loss is in the first order a function of the plasma system dimensions and geometry The decay of Te (t ) depends on loss and the losses due to inelastic scattering

Design procedure for compact pulse transformers with rectangular pulse shape and fast rise times

Abstract: Pulse modulators based on solid state technology and for pulses in the μs-range often utilize a pulse transformer, since it could offer an inherent current balancing for parallel connected power semiconductors and the turns ratio of the pulse transformer allows to adapt the modulator design to the available switch technology. The applications like radar systems, linear accelerators or klystron/magnetron modulators usually require a nearly rectangular pulse shape with a fast rise time and a as small as possible overshoot. In reality however, parasitic elements of the pulse transformer as leakage inductance and capacitances limit the achievable rise time and define the resulting overshoot. Therefore, in modulators based on pulse transformers, the design of the pulse transformer is crucial. In this paper, a step by step design procedure of a pulse transformer for rectangular pulse shape with fast rise time is presented. Different transformer topologies are compared with respect of the parasitic elements, which are then calculated analytically depending on the mechanical dimensions of the transformer. Additionally, the influence of the limited switching speed of semiconductors and the nonlinear impedance characteristic of a klystron is analyzed.