Spectral irradiance scale realization and uncertainty analysis based on a 14 mm diameter WC-C fixed point blackbody from 250 nm to 2500 nm

Spectral irradiance scale in the wavelength range from 250 nm to 2500 nm was realized at National Institute of Metrology (NIM) on the basis of a large area tungsten carbide–carbon (WC-C) high temperature fixed point blackbody, which is composed of a 14 mm diameter WC-C fixed point cell and a variable temperature blackbody BB3500MP as a furnace. A series of 1000 W FEL tungsten halogen lamps were used as transfer standards. The new spectral irradiance scale was compared with the scale based on a variable-temperature blackbody BB3500M, and the divergence between these two methods varied from -0.66% to 0.79% from 280 nm to 2100 nm. The measurement uncertainty of spectral irradiance scale based on fixed-point blackbody was analyzed, and the expanded uncertainty was estimated as 3.9% at 250 nm, 1.4% at 280 nm, 0.43 % at 400 nm, 0.27% at 800 nm, 0.25% at 1000 nm, 0.62% at 1500 nm, 0.76% at 2000 nm, and 2.4% at 2500 nm respectively. In the range from 300 nm to 1000 nm the fixed-point scale was improved obviously: the uncertainty decreased by more than 25% compared to the uncertainty based on the variable temperature blackbody. Below 300 nm, the uncertainty became higher because the signal to noise ratio was poor. Above 1100 nm, the contribution of temperature measurement to the uncertainty of spectral irradiance decreases, therefore the uncertainties of two methods are almost at the same level. The fixed-point blackbody was also used to realize the correlated colour temperature and distribution temperature of a tungsten filament lamp, the deviation from the variable temperature blackbody method was -0.5 K and -2.9 K, respectively.

Fluorescent lamp tungsten filament thermionic emission gun as a novel humidity optical sensor

Detecting humidity have been remained a continuing concern within some important areas such as structural health, food processing, industrial as well as agricultural products. In this study, a novel humidity optical sensor is introduced based on the thermionic emission of tungsten filament using the fluorescent lamp set-up. Estimated blue compliant using a charged coupling device camera in optical image of the tungsten filament was confirmed as an appropriate detection system for relative humidity (RH) sensing. The fabricated optical sensor has wide linear range (2.0–98% RH), improved detection limit (< 5.0% RH), acceptable saturated limit (> 99.0% RH), improved percentage of relative standard deviation (4.18%, n = 2), adequate hysteresis (< 4.0% RH) and a shorter rise time (< 5.0 s), respectively. The mechanism behind this detection system is based on the interaction between H2O and tungsten filament during formation of W$${\mathrm{O}}_{3}$$ O 3 .x $${\mathrm{H}}_{2}$$ H 2 O (x = 1–2) in terms of some spectroscopic obtained evidences as well as Fourier transform infrared and X-ray diffraction spectrometries.

ION GENERATION BY TUNGSTEN FILAMENT FOR PYROELECTRIC PULSED ACCELERATOR

The article is devoted to investigation of ion generation by tungsten filament in vacuum. Electron and ion currents from tungsten filament at different residual air gas pressures are measured and compared. Dependencies of ion and electron currents from tungsten filament on its supply voltage are measured. Production of ions in the vicinity of the filament is discussed. Prospects of tungsten filament’s application in pyroelectric and piezoelectric pulsed accelerators are discussed.

Fluorescent lamp tungsten filament thermionic emission gun as a novel humidity optical sensor

Detecting humidity is a continuing concern within important area such as structural health, food processing, industrial as well agricultural products. In this study, a novel humidity optical sensor is introduced based on the thermionic emission of tungsten filament of a fluorescent lamp. Estimated blue compliant using a charged coupling device camera (CCD) in optical image of the tungsten filament is considered as appropriate detection system for relative humidity (RH) sensing. . The fabricated optical sensor has acceptable linear range (2.0- 98 % RH), improved detection limit (<5.0 % RH), acceptable saturated limit (> 99.0 % RH), improved percentage of relative standard deviation (4.18%, n=2), adequate hysteresis (<4.0 % RH) and a shorter rise time (<5.0 s), respectively. The mechanism behind this detection system was based on the interaction between H2O and tungsten filament during formation of WO3.x H2O (x = 1-2) based on the patented X-ray diffraction analysis.

Study on the Validity of Wien’s Displacement Law on Tungsten Bulb

This work was mainly based on three interdependent parameters, which are temperature, emissivity and peak emission wavelength. Temperature is the primary parameter that determines how much light the filament gives off, and at what wavelengths. The work was focused on temperature determination of tungsten filament with different values of emissivity. The different values of emissivity taken for the work were 0.433, 0.431, 0.427, 0.421 and 0.415. Peak emission wavelength was calculated at different tungsten temperatures for different wattage bulbs which was in the order of 10-6m. 6, 60, and 500 watt bulb were taken for the work. The peak of the spectrum lay in the infrared region. Wien’s displacement law was used to calculate the value of peak emission wavelength. The work was based on theoretical model. Blackbody spectrum curve was used to analyze the emitted radiations from the bulb. In each spectrum curve, radiations having higher wavelengths were emitted in greater amount than the radiations having lower wavelength. Spectral radiance was found to be dependent upon both emissivity and power of the bulb. The area under the blackbody spectrum curve indicated the total number of emitted radiations and hence the total energy radiated across all wavelengths. The total energy emitted from tungsten filament was found to be increased rapidly with temperature. Brightness of the bulb increased with the increase in temperature of the tungsten. The peak in the blackbody spectrum curve shifts towards left, when temperature increased. There is a direct consequence of the brightness of bulb with the peak emission wavelength.