نتایج جستجو برای: pre ionization
تعداد نتایج: 349227 فیلتر نتایج به سال:
in this paper, we calculate electron and hole impactionization coefficients in in0.52al0.48as using a monte carlo modelwhich has two valleys and two bands for electrons and holesrespectively. also, we calculate multiplication factor for electronand hole initiated multiplication regimes and breakdown voltagein in0.52al0.48as pin avalanche photodiodes. to validate themodel, we compare our simulat...
conclusions the state of observed radiation protection principles was relatively in the weak level in the studied radiology departments especially in facilities such as ventilation system, radiography entrance, and darkroom situation. more important reason was usage changing of sections as radiology billet from related organizations. results the mean of radiation protection in the studied radio...
background: the aim of this work was to study the output factors for linac using different ionization chambers and build up caps. materials and methods: output factors were measured for open square fields (3 × 3 cm to 40 × 40 cm) defined by collimator jaws for 6 and 15 mv photon beams from a varian clinac 2100c accelerator were measured. the measurements in air were performed using compact cyli...
Although both 1 harmonic ordinary mode (O1) and 2 harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH ...
Electron energy-loss spectroscopy (EELS) has become a standard tool for identification and sometimes also quantification of elements in materials science. This is important for understanding the chemical and/or structural composition of processed materials. In EELS, the background is often modelled using an inverse power-law function. Core-loss ionization edges are superimposed on top of the do...
A comparison of detection limits of gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) with gas chromatography-tandem mass spectrometry (GC-MS/MS) in selected reaction monitoring (SRM) mode with both electron ionization (EI) and negative-ion chemical ionization (NCI) are presented for over 50 pesticides ranging from organochlorines (OCs), organophosphorus pesticides (...
An electrically floating radiofrequency (RF) pre-ionization plasma source has been developed to enable neutral gas breakdown at lower pressures and to access new experimental regimes in the Caltech laboratory astrophysics experiments. The source uses a customized 13.56 MHz class D RF power amplifier that is powered by AA batteries, allowing it to safely float at 3-6 kV with the electrodes of th...
یکی از مهم ترین مشکلات سیستم های ofdm عدم توانایی این سیستم ها در حذف سیگنال تداخل در باند فرکانسی سیگنال مطلوب می باشد. برای حذف این تداخلات از روش های شکل دهی پرتو استفاده می شود. دو روش مرسوم شکل دهی پرتو، روش pre-fft (شکل دهی پرتو در حوزه زمان) و روش post-fft (شکل دهی پرتو در حوزه فرکانس) می باشند. برای به روزرسانی وزن ها در هر دو روش راه حل های مختلفی پیشنهاد شده است که می توان همه آن ها ر...
The use of gaseous ionization to calculate the absorbed dose of radiation beams is attractive because of its relative ease, suitable response, high accuracy and also cost-effectiveness. This work introduces the design and fabrication of a new parallel plate ionization chamber with two sensitive volumes. A series of standard tests was performed with x-rays, gamma radiation units, and beta source...
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