Spatially resolved behavior of laser-produced copper plasma along expansion direction in the presence of static uniform magnetic field

We report on the spatially resolved optical emission spectroscopic study of laser-produced copper plasma in the presence of static uniform magnetic field in air ambient at atmospheric pressure. The response of copper atomic/ionic lines to magnetic field along the axial direction of plasma is different. It is attributed to the difference in populating process (electron impact excitation and recombination) of each transition. In the present work, we introduced air pressure to calculate the stopping radius and found it to be around the distance at which the intensity is pronounced. The electron density varied as ne = 9.2z−0.33 without magnetic field and in the presence of 0.3 T magnetic field, it varied as ne = 7.9z−0.27. The electron temperature variation with distance from the target in the absence and presence of magnetic field is found to be Te = 1.1z−0.23 and Te = 0.9z−0.18. The electron density and temperature decay slowly along the plasma expansion direction in the presence of magnetic field. It is due to magnetic confinement of plasma. We demonstrated that the thermal conductivity of plasma is enhanced in the presence of magnetic field. From the spatial evolution of the electron density and temperature, we estimated the approximate dimension of the core and tail region of the plasma and found an increase in the core dimension in the presence of magnetic field. The increase in core dimension is in agreement with the intensity variation of ionic line. It is attributed to an increase in heat transfer due to an increase in thermal conductivity in the presence of magnetic field. The present work may help optimize the distance from target to enhance spectral line intensity in optical emission spectroscopy in the presence of magnetic field.