Time-resolved Cavity Ringdown Spectroscopy as a Monitoring Technique of Nanoparticles in Pulsed VHF Plasmas

2007 ◽  
Vol 989 ◽  
Author(s):  
Takehiko Nagai ◽  
Arno H. M. Smets ◽  
Michio Kondo
Keyword(s):  
Time Scales ◽  
Rayleigh Scattering ◽  
Mie Scattering ◽  
Nano Particles ◽  
Initial Growth ◽  
Time Resolved ◽  
Cavity Ringdown ◽  
Plasma Ignition ◽  
Cavity Loss ◽  
Small Constant

AbstractTime-resolved cavity ringdown (τ-CRD) spectroscopy has been applied to monitor the sylil (SiH3) radicals and nano-particles in pulsed very high frequency (VHF) silane (SiH4)/hydrogen (H2) plasmas under microcrystalline silicon (μc-Si:H) deposition conditions. After the plasma ignition, a small constant cavity loss (~100 ppm) on timescales smaller than ~1 s has been observed, whereas on time scales larger than ~1 s after plasma ignition, an additional cavity loss is observed. By variation of the wavelength of the CRD laser pulse, we demonstrate that the cavity loss on time scales smaller than ~1 s reflects the SiH3 absorption. On time scales larger than ~1 s, the additional cavity loss corresponds to the loss of light due to mainly scattering at the nano-particles. Under the conditions studied, the light scattering at nano-particles can be described by Rayleigh scattering during its initial growth. After ~ 2.5 s, the cavity loss reflects the transition of the scattering mechanism from dominant Rayleigh to dominant Mie-scattering. These results are discussed in terms of nano-particles growing in time and further confirmed by additional scanning electron microscopy analyses on the nano-particles created in the plasma pulse.

Detection of SiH3 radicals and cluster formation in a highly H2 diluted SiH4 VHF plasma by means of time resolved cavity ring down spectroscopy

2006 ◽  
Vol 910 ◽  
Author(s):  
Takehiko Nagai ◽  
Arno H. M. Smets ◽  
Michio Kondo
Keyword(s):  
Growth Rate ◽  
Cluster Formation ◽  
Film Surface ◽  
Growth Conditions ◽  
Time Resolved ◽  
Cavity Ringdown ◽  
Plasma Ignition ◽  
Diffusion Controlled ◽  
Kinetics Of ◽  
Main Growth

AbstractThe spatial distribution of the SiH3 radicals between the electrodes of a hydrogen diluted silane VHF plasma under thin film hydrogenated microcrystalline silicon (μc-Si:H) growth conditions has been measured using the time resolved cavity ringdown (τ-CRD) absorption spectroscopy technique. The μc-Si:H growth rate is estimated from the measured spatial SiH3 profiles using a simple model based upon diffusion controlled flux of SiH3 radicals to the electrode surface, where the SiH3 can react with the film surface. The calculated value of μc-Si:H growth rate roughly agrees with the value of the experimentally determined growth rate. This agreement implies that the SiH3 radical is the main growth contributor to the μc-Si:H growth. Furthermore, the τ-CRD reveals the growth kinetics of the clusters in the plasma by light scattering at these clusters on time scales of 1 s after the plasma ignition.

scholarly journals Time Resolved Emission of Sidestream Smoke Particles

1992 ◽  
Vol 15 (2) ◽  
pp. 53-57
Author(s):  
R Dittmann ◽  
HJ Feld ◽  
BH Müller ◽  
W Schneider
Keyword(s):  
Time Scales ◽  
Time Resolved ◽  
Smoke Particles ◽  
Sidestream Smoke ◽  
Different Types ◽  
Short Time ◽  
Aerosol Properties

AbstractBy means of the dispersion quotient method, the aerosol properties of freshly produced sidestream smoke were measured during the puff and subsequent interpuff period. These measurements were made on short time scales and at high aerosol concentrations. Examples are presented, which show the influence of different combustion conditions during the puff (resulting from different degrees of ventilation and different types of tobacco) on the emission of sidestream particles during the interpuff period. The ratio of the volume concentrations of the particles before and during a puff is reduced by ventilation and is nearly unchanged by the variation of the tobacco type.

scholarly journals Temperature lidar measurements from 1 to 105 km altitude using resonance, Rayleigh, and Rotational Raman scattering

2004 ◽  
Vol 4 (1) ◽  
pp. 923-938 ◽  
Author(s):  
M. Alpers ◽  
R. Eixmann ◽  
C. Fricke-Begemann ◽  
M. Gerding ◽  
J. Höffner
Keyword(s):  
Metal Layer ◽  
Lower Thermosphere ◽  
Atmospheric Temperature ◽  
Mie Scattering ◽  
Temperature Profiles ◽  
Calculation Algorithm ◽  
Time Resolved ◽  
Atmospheric Physics ◽  
Rayleigh Backscattering ◽  
Spectral Doppler

Abstract. For the first time, three different temperature lidar methods are combined to obtain time-resolved complete temperature profiles with high altitude resolution over an altitude range from the planetary boundary layer up to the lower thermosphere (about 1–105 km). The Leibniz-Institute of Atmospheric Physics (IAP) at Kühlungsborn, Germany (54° N, 12° E) operates two lidar instruments, using three different temperature measurement methods, optimized for three altitude ranges: (1) Probing the spectral Doppler broadening of the potassium D1 resonance lines with a tunable narrow-band laser emitter allows the determination of atmospheric temperature profiles at the metal layer altitudes (80–105 km). (2) Between about 20 and 90 km, temperatures were calculated from Rayleigh backscattering on air molecules, where the upper start values for the calculation algorithm were taken from the potassium lidar results. Correction methods have been applied to account for, e.g. Rayleigh extinction or Mie scattering of aerosols below about 32 km. (3) At altitudes below about 25 km, backscattering on the Rotational Raman lines is strong enough to obtain temperatures by measuring the temperature dependent spectral shape of the Rotational Raman spectrum. This method works well down to about 1 km. The instrumental configuration of the IAP lidars was optimized for a 3–6 km overlap of the temperature profiles at the method transition altitudes. First night-long measurements show clear wave structures propagating from the lower stratosphere up to the lower thermosphere in most of the nights.

Time-resolved Hyper-Rayleigh Scattering

2004 ◽  
Author(s):  
T. Buckup ◽  
J. Schoffen ◽  
R. R.B. Correia ◽  
S. L.S. Cunha ◽  
M. Motzkus
Keyword(s):  
Rayleigh Scattering ◽  
Time Resolved

The Polarization Properties Research of Atmospheric Based on Actual Weather Conditions

2014 ◽  
Vol 556-562 ◽  
pp. 933-936
Author(s):  
Fei Zhang ◽  
Xiao Ping Du ◽  
Shen Wang
Keyword(s):  
Rayleigh Scattering ◽  
Weather Conditions ◽  
Mie Scattering ◽  
New Method ◽  
Degree Of Polarization ◽  
Scattering Angle ◽  
Polarization Characteristics ◽  
Simulation Results

A new method to calculate the polarization properties of the atmosphere by combining the Rayleigh scattering and Mie scattering is proposed in this paper. We inversed the values of the required data by experiment and simulated of the atmosphere polarization characteristics under the same conditions. The simulation results show that the proposed method can accurately describe the variation of the atmosphere polarization properties. Besides, the results show such variation: in the same weather conditions, the degree of polarization is gradually increased while scattering angle is gradually increased as 90°; in the same detect conditions, the degree of polarization decreases with the deteriorating weather conditions.

scholarly journals Non-steady wind turbine response to daytime atmospheric turbulence

2017 ◽  
Vol 375 (2091) ◽  
pp. 20160103 ◽  
Author(s):  
Tarak N. Nandi ◽  
Andreas Herrig ◽  
James G. Brasseur
Keyword(s):  
Field Experiment ◽  
Wind Turbine ◽  
Atmospheric Turbulence ◽  
Time Scales ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Atmospheric Conditions ◽  
Time Resolved ◽  
Eddy Simulation ◽  
Large Eddy

Relevant to drivetrain bearing fatigue failures, we analyse non-steady wind turbine responses from interactions between energy-dominant daytime atmospheric turbulence eddies and the rotating blades of a GE 1.5 MW wind turbine using a unique dataset from a GE field experiment and computer simulation. Time-resolved local velocity data were collected at the leading and trailing edges of an instrumented blade together with generator power, revolutions per minute, pitch and yaw. Wind velocity and temperature were measured upwind on a meteorological tower. The stability state and other atmospheric conditions during the field experiment were replicated with a large-eddy simulation in which was embedded a GE 1.5 MW wind turbine rotor modelled with an advanced actuator line method. Both datasets identify three important response time scales: advective passage of energy-dominant eddies (≈25–50 s), blade rotation (once per revolution (1P), ≈3 s) and sub-1P scale (<1 s) response to internal eddy structure. Large-amplitude short-time ramp-like and oscillatory load fluctuations result in response to temporal changes in velocity vector inclination in the aerofoil plane, modulated by eddy passage at longer time scales. Generator power responds strongly to large-eddy wind modulations. We show that internal dynamics of the blade boundary layer near the trailing edge is temporally modulated by the non-steady external flow that was measured at the leading edge, as well as blade-generated turbulence motions. This article is part of the themed issue ‘Wind energy in complex terrains’.

Design and Compiling of Laser Propagation Simulation Software in Atmospheric Environment

2012 ◽  
Vol 490-495 ◽  
pp. 2136-2140
Author(s):  
Tong Gang Zhao ◽  
Zhi Qiang Zhang
Keyword(s):  
Theoretical Model ◽  
Rayleigh Scattering ◽  
Hot Spot ◽  
Theoretical Models ◽  
Mie Scattering ◽  
Simulation System ◽  
Simulation Software ◽  
Atmospheric Environment ◽  
Laser Propagation ◽  
Atmospheric Propagation

As development of laser technology, the characteristic of laser atmospheric propagation is always hot spot in laser domain. Using theoretical models of laser atmospheric propagation, a simulation system is researched by implementing a scientific method of software development. This simulation system can simulate the radiate property of laser propagation in atmosphere, and demonstrate the course of laser propagation. This theoretical model of atmospheric propagation is based on Lambert-Beer law, combined with other classic theoretical model such as Rayleigh scattering and Mie scattering. Multiple scattering theories are used when simulating the laser propagation in smoke or fog. In calculation, the atmosphere is divided into layer. An appropriate model will be selected for calculation in each layer in order to enhance the stimulation precision. Lastly, the figure of light spot is drawn along with transmission space. Laser atmospheric propagation is demonstrated.

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