A New Method of Measurement of the True Temperature and Emissivity of Non-Black Body Using One Component of Wien’s Spectrum of Thermal Radiation

It is shown that the measurement of only one component of the Wein’s spectrum of thermal radiation in range λT ≤ 3000 (°C μm) is sufficient to estimate the true temperature and spectral emissivity of the selected component with sufficient accuracy, although more than one hundred years this statement was considered as incorrect. The proposed method is based on the formation of the linear dependence of the logarithm of the emissivity of not real wavelengths and artificially generated “virtual” spectral components.

A comparison of emissive and cold floating probe techniques for electric potential measurements in rf inductive discharge

A cold floating probe method was compared with the emissive floating probe method in terms of a low-pressure radio-frequency inductive discharge.The dependences of difference between the plasma potential and the floating potential on the electron temperature 1-8 eV,plasma density 109-1012 cm 3 and magnetic field 100-650 G were obtained.It was demonstrated that the difference between the potentials that obtained by these two methods can differ significantly from the expected value of 5.2 kTe/e for argon.

Application of quantum-statistical methods to studies of thermodynamic and radiative processes in hot dense plasmas

Calculations of thermodynamic and radiative characteristics of hot dense plasmas within different quantum-statistical approaches,such as the use of the Hartree–Fock–Slater model and the ion model,are presented.Calculated equations of state of different substances are used to investigate findings from absolute and relative measurements of the compressibility of solid aluminum samples in strong shock waves.It is shown that our calculated Hugoniot adiabat of aluminum is in a good agreement with experimental data and other theoretical results from first principles.Wealso present a review of the most important applications of the quantum-statistical approach to the study of radiative properties of hot dense plasmas.It includes the optimization problem of hohlraum wall materials for laser inertial fusion,calculations of the radiative efficiency of complex materials for optically thin plasma in X-pinch,modeling of radiative and gas-dynamic processes in plasma for experiments,where both intense laser and heavy ion beams are used,and temperature diagnostics for X-and Z-pinch plasmas.

Precise wavelength measurements of potassium He- and Li-like satellites emitted from the laser plasma of a mineral target

Atomic models of high-Zmulticharged ions are extremely complex and require experimental validation.Oneway to do so is to crosscheck the predicted wavelengths of resonance transitions in He-and Li-like ions against precise spectroscopic measurements that use the spectral lines of H-like ions for spectra calibration;these reference data can be modeled with outstanding precision.However,for elements with Z of at least 15,it is quite difficult to create a hot dense plasma with a large concentration ofH-like charge states.To mitigate this issue,the suggestion here is to use as laser targets particular minerals comprising elements with moderate(between 15 and 30)and low(less than 15)Z,with emission from the latter delivering perfect reference lines over a whole range o fHe-and Li-like moderate-Z emission under examination.This approach is implemented to measure the wavelengths of resonance transitions(1snp→1s^(2) for n=2,3)in He-likeKions and their dielectronic satellites by irradiating plates of orthoclase(KAlSi_(3)O_(8))with0.5-kJ subnanosecond laser pulses.X-ray spectra of the laser-generated plasma contain the investigated lines of highly charged K-ions together with precisely known reference lines of H-like Al and Si atoms.The K-shell spectral line wavelengths are measured with a precision of around 0.3 mA.

Optimization of a laser plasma-based x-ray source according to WDM absorption spectroscopy requirements

X-ray absorption spectroscopy is a well-accepted diagnostic for experimental studies of warm dense matter.It requires a short-lived X-ray source of sufficiently high emissivity and without characteristic lines in the spectral range of interest.In the present work,we discuss how to choose an optimum material and thickness to get a bright source in the wavelength range 2A–6A(∼2 keV to 6 keV)by considering relatively low-Z elements.We demonstrate that the highest emissivity of solid aluminum and silicon foil targets irradiated with a 1-ps high-contrast sub-kJ laser pulse is achieved when the target thickness is close to 10μm.An outer plastic layer can increase the emissivity even further.

Regimes of near-stoichiometric hydrogen/air combustion under reciprocating engine conditions

1Introduction Hydrogen/air combustion is a problem both in respect of its fundamental science and in the use of hydrogen as a possible substitute for traditional hydrocarbon fuels.There is now a generally agreed approach to the use of hydrogen as an addition to traditional fuels(He et al.,2017)but the use of hydrogen as a main fuel has been studied much less because of the substantially unresolved problems for effective hydrogen production(Liu et al.,2020).It is worth noting that the use of hydrogen as a main fuel may be primarily applied not only for internal combustion engines needed for transport(Balat,2008),but also for those serving as drives for electrogenerators within stationary power stations(Balat,2008;Ivanov et al.,2018).