In this paper, the development of large volume double ring Penning plasma discharge source for efficient light emissions is reported. The developed Penning discharge source consists of two cylindrical end cathodes of stainless steel having radius 6 cm and a gap 5.5 cm between them, which are fitted in the top and bottom flanges of the vacuum chamber. Two stainless steel anode rings with thickness 0.4 cm and inner diameters 6.45 cm having separation 2 cm are kept at the discharge centre. Neodymium (Nd(2)Fe(14)B) permanent magnets are physically inserted behind the cathodes for producing nearly uniform magnetic field of ~0.1 T at the center. Experiments and simulations have been performed for single and double anode ring configurations using helium gas discharge, which infer that double ring configuration gives better light emissions in the large volume Penning plasma discharge arrangement. The optical emission spectroscopy measurements are used to complement the observations. The spectral line-ratio technique is utilized to determine the electron plasma density. The estimated electron plasma density in double ring plasma configuration is ~2 × 10(11) cm(-3), which is around one order of magnitude larger than that of single ring arrangement.

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Pseudospark discharge is a specific type of gas discharge, which operates on the left-hand side of the hollow cathode analogy to the Paschen curve with axially symmetric parallel electrodes and central holes on the electrodes [1-2]. The discharge is characterized by a very rapid breakdown phase; during which high-density particle beams can be extracted and rapid increasing rate of current can be achieved. The initiation phase of Pseudospark discharges is very important in the whole hollow cathode discharge procedure because of it has direct influence to parameters of discharge current, stability, pulse width, amplitude, switching time and so on. The theoretical studies of the Pseudospark discharges have been carried out. A theoretical and plasma simulation model has been adopted to study the initiation phase of Pseudospark discharges. The pre-breakdown and breakdown phases of a Pseudospark discharge are investigated using the two-dimensional kinetic plasma simulation code OOPIC Pro [3].Trends in the electron density at the anode are presented as function of the hollow cathode dimensions and mean seed injection velocities at the cavity back wall. The plasma generation process by ionizing collisions is examined, showing the effect on supplying electrons that determine the density of the beam. The growth phenomena is dependent on the Townsend coefficient due to local space charge from initial ionization growth to onset of the hollow cathode effect, and then hollow cathode effect become leading factor. The experiment has also been performed for the analysis of the pseudospark discharge Fig (1): Simulation Model, Full Sectional View of single gap PSS, Paschen curveTo investigate the geometrical effect of electrodes in hollow cathode. We consider two cases of energy for simulation. Case (1) vx =1000 and emitter current 10 amp. With a temperature 2.5 eV and injection period 1 ns. Case (2): vx=500 and emitter current 4 amp. With a temperature 1.5 eV and injection period 100 ns. In these cases the discharge is filled with Hydrogen gas at room temperature and at a pressure of approximately 35 Pascal with an anode voltage 10 kV and a grounded cathode.

In the present work an effort has been made to estimate the plasma parameters simultaneously like-electron density, electron temperature, ground state atom density, ground state ion density and metastable state density from the observed visible spectra of penning plasma discharge (PPD) source using least square fitting. The analysis is performed for the prominently observed neutral helium lines. The atomic data and analysis structure (ADAS) database is used to provide the required collisional-radiative (CR) photon emissivity coefficients (PECs) values under the optical thin plasma condition in the analysis. With this condition the estimated plasma temperature from the PPD is found rather high. It is seen that the inclusion of opacity in the observed spectral lines through PECs and addition of diffusion of neutrals and metastable state species in the CRmodel code analysis improves the electron temperature estimation in the simultaneous measurement.

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