scholarly journals A Study of Current Controlled Discharge in a Nitrogen Filled Tube

2021 ◽  
Vol 11 (21) ◽  
pp. 10253
Author(s):  
Michal Nevrkla ◽  
Jakub Hubner ◽  
Jiri Sisma ◽  
Pavel Vrba ◽  
Miroslava Vrbova ◽  
...  
Keyword(s):  
Laser Beam ◽  
Electron Density ◽  
Electrical Resistance ◽  
Computer Modelling ◽  
Sapphire Laser ◽  
Time Development ◽  
Laboratory Results ◽  
Time Dependencies ◽  
Computer Codes ◽  
A Current

Time dependencies of the electrical resistance and electron density evolution in the discharge in a tube, with nitrogen at different pressures, with a diameter of 9.2mm and a length of 10cm were studied. A current pulse with an amplitude of 500A and duration of 10μs has created the discharge in the tube. Instantaneous electron densities are estimated from the interference pattern in Mach–Zehnder interferometer using femtosecond Ti: sapphire laser beam. Laboratory results are compared with results of computer modelling by MHD computer codes NPINCH and ZSTAR. Time development of the discharge resistance according to experiment is measured and evaluated. Minimum measurable value of the electron density in the experiment is determined as 2×1015cm−3.

scholarly journals The effect of temperature on structural changes of NI55CO45 amorphous powder

2004 ◽  
Vol 36 (2) ◽  
pp. 105-112 ◽  
Author(s):  
M. Spasojevic ◽  
Aleksa Maricic ◽  
Lidija Rafailovic
Keyword(s):  
Current Density ◽  
Electrical Resistance ◽  
Structural Changes ◽  
Crystallization Process ◽  
Amorphous Powder ◽  
Solution Temperature ◽  
Specific Chemical ◽  
A Current ◽  
Shape And Size ◽  
Cobalt And Nickel

Cobalt and nickel alloy powders were obtained by electrochemical deposition on a titanium cathode from an ammonium solution of cobalt and nickel sulfate. Powders of a specific chemical structure and composition, particle shape and size were obtained by an appropriate choice of electrolysis parameters, current density, deposit growth rate and solution temperature and composition. Within the current density range of 5 - 450 mAcm-2, the current density did not significantly affect the chemical composition of the powders, but had a significant effect on the particle structure, shape and size. Crystal particles formed at a current density lower than 30 mAcm-2. Amorphous powders were obtained at a current density higher than 50 mAcm-2. Structural changes of the obtained amorphous powder of 55mol.% Ni, 45 mol.% Co, pressed under the pressure of 100 MPa, were investigated by measuring the temperature dependence of electrical resistance in isothermal and non-isothermal conditions varying from room temperature to 750?C. The process of thermal stabilization of defects that appeared during pressing occurred within the temperature range of 200-390?C. The DSC method was used to determine that the powder crystallization process occurred in two stages with peak temperatures of the exothermal maximum in the first and second stage of T1 = 438?C and T2 = 573?C, respectively. A distinct correlation between the change of electrical resistance and the crystallization process was established. The reduction of electrical resistively occurs during each crystallization stage.

scholarly journals A note on 20-species lists

1997 ◽  
Vol 7 (3) ◽  
pp. 293-293 ◽  
Author(s):  
Bent Otto Poulsen ◽  
Niels Krabbe ◽  
Amy Frølander ◽  
Marcelo B. Hinojosa ◽  
Carmen O. Quiroga
Keyword(s):  
Relative Abundance ◽  
Computer Modelling ◽  
True Number ◽  
Species Lists ◽  
Relative Abundances ◽  
Number Of Individuals ◽  
A Current ◽  
Modelling Study

Since our paper on the efficiency and biases of 20-species lists (Poulsen et al. 1997) went to press we have recognized a further two biases in the method, after discussions with C. Rahbek. We remarked in our paper that the abundance curves were behaving rather strangely and that “the importance of these phenomena needs to be investigated in more detail”. The behaviour may be due to the method setting constraints on the highest possible frequency, namely the number of times a species occurs in 20-species lists. This could affect the calculation of the expected abundances and hence the a-index. Another bias must be the indirect way of determining the relative abundances, ignoring the true number of individuals. A species with many individuals will be given the same relative abundance as a species with very few individuals if both species occur in the same number of 20-species lists. We do not know the importance of these constraints but recommend that the method is not used until the results of a current computer modelling study examining its efficiency (S. Herzog and M. Kessler pers. comm.) are known.

scholarly journals Scaling of plasmas, heated and ponderomotively confined by powerful laser radiation

1998 ◽  
Vol 16 (2) ◽  
pp. 235-252 ◽  
Author(s):  
V.V. Korobkin ◽  
M. Yu. Romanovsky
Keyword(s):  
Laser Radiation ◽  
Laser Beam ◽  
Electron Density ◽  
Dense Plasma ◽  
Critical Density ◽  
Thermonuclear Fusion ◽  
Powerful Laser ◽  
Controlled Thermonuclear Fusion

It is shown that a powerful laser beam is capable of the ponderomotive confinement of plasma with electron density exceeding the critical density for the radiation under review. The theory describing force and heat balances of the plasma together with the propagation of the laser radiation is developed. The laws of the dense plasma scaling for controlled thermonuclear fusion (CTF) and other applications are formulated.

Computer modelling of laser-beam welding: Model and verification

1997 ◽  
Vol 11 (7) ◽  
pp. 567-573 ◽  
Author(s):  
V A Sudnik ◽  
D Radaj ◽  
V A Erofeev
Keyword(s):  
Laser Beam ◽  
Computer Modelling ◽  
Laser Beam Welding
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