A small plasma focus (3.3 kJ) is designed from the viewpoint of simplicity, reliability, and cost effectiveness to act as a source of pulsed high-density plasmas. The simplicity of the device and associated diagnostics coupled with its rich variety of plasma phenomena makes this device ideal for the teaching of plasma nuclear fusion particularly for developing countries where such facilities are at present rarely available. Six sets of the device have been constructed and tested in various gases with better than 95% reliability and reproducibility in various plasma phenomena including neutron production of 0.5–1.0×108 per discharge when operated in 3-Torr deuterium. The design principles, procedures, and parameters are discussed and test results shown.

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In a low energy (2.3 kJ) Mather-type deuterium plasma focus, neutron and charged particle emission is investigated by using time-resolved neutron detectors and time-integrated charged particle pinhole imaging camera. The time-integrated charged particle pinhole images demonstrate the varying influence of magnetohydrodynamic (MHD) instabilities vis-a-vis filling pressure. The neutron production mechanism at play strongly depends upon the pressure. At lower pressure, the plasma column is highly unstable due to MHD instabilities and the neutron emission is found to be low with fluence anisotropy exceeding 3.5. At optimum pressure (2.5 mbar for this system), an almost stable dense plasma of about 17 mm3 volume is formed about 5 mm away from the anode, with neutron emission at its highest and the fluence anisotropy lowest. At higher pressure, the plasma column is stable, although it moves away from the anode like a jet and may then be called a moving boiler. In this case, the neutron emission is lowered compared to its optimum value and fluence anisotropy is increased. The data suggest beam-target mechanism at low pressure, trapped gyrating particles at optimum pressure and a jetlike moving boiler at higher pressure.

Optical emission spectroscopy of the active species in N 2 plasma is carried out to investigate their concentration as a function of discharge parameters such as filling pressure (2.0-7.0 mbar), source power (100-200 W) and gas flow rate (50-300 mg/min). The primary motivation of this work is to obtain reliable information about the concentration of the active species of N 2 plasma, which play an important role in plasma surface nitriding processes. Emission intensity from the selected electronic excited states of molecular and atomic species is evaluated as a function of discharge parameters to investigate their concentration. The emission intensity ratio I (N + 2 )/I (N 2 ) and I (N + )/I (N ) of the electronic transitions is also evaluated as a function of discharge parameters to investigate the relative dependence of their concentrations. It is observed that the concentration of the active species of N 2 plasma is strongly affected by the filling pressure and source power whereas flow rate has no significant effect. An increased occurrence of N + 2 molecular ions in comparison with N 2 molecules, and N + ions in comparison with N atoms is observed with source power whereas decreased occurrence of N + 2 molecular ions in comparison with N 2 molecules, and N + ions in comparison with N atoms is observed with the rise in filling pressure.

The room temperature nitriding of titanium is accomplished by utilizing nitrogen ion beams delivered by a 2.3 kJ plasma focus discharge. Titanium samples are exposed to ions at different axial positions (3, 5, 7 and 9 cm from the focus) in order to correlate their surface properties with ion beam parameters such as energy, number density, current density and energy flux (energy deliverance per unit time per unit volume). A BPX65 photodiode detector is employed to measure the ion beam parameters by using the time of flight technique. X-ray diffraction analysis as well as field emission scanning electron microscopy along with the energy dispersive x-ray spectroscopy is carried out to explore the structural, morphological and compositional profiles of the treated samples. The results demonstrate the formation of nanocrystalline TiN thin film with surface features strongly dependent on ion beam energy flux. A Vickers microindentation measurement reveals that the surface hardness is improved 4–5 times for typical nitrided samples.