Some studies on picosecond laser produced plasma expanding across a uniform external magnetic field

Abstract

Some characteristics of the picosecond laser produced plasma expanding across an externally applied magnetic field (0.6 T) have been reported. Two to three times enhancement in X-ray emission from copper plasma has been observed for the laser intensity range ~5 X 10" to 5 X 10 12 W/cm 2 . The X-ray yield has been found to increase with an increase in the magnetic field intensity. Enhancement in X-ray emission is correlated with confinement of expanding plasma either in external magnetic field or in high ambient gas pressure. Generation of some highfrequency instability and fast ions was also observed in the plasma along with bouncing of plasma near the ft = 1 surface where kinetic pressure of plasma equals magnetic pressure.

Laser-induced breakdown spectroscopy to monitor ion cyclotron range of frequency wall cleaning Li/D co-deposition in EAST tokamak

“…According to the theoretical work by Rai et al [34][35][36], the ratio (I 2 /I 1 ) of plasma emission intensity in the presence and in the absence of a magnetic field can be written as: (1) where I 1 , I 2 is plasma emission intensity in B=0 and B ≠ 0, respectively; 8πnk ⁄ , is the ratio of the kinetic energy of the plasma to the magnetic energy; t 1 , t 2 is the duration of spectral emission without and with the magnetic field, respectively; n, T e and k are the amount of substance, electron temperature and Boltzmann's constant, respectively. Equation (1) indicates that enhancement ( ) in emission intensity is possible only when plasma β is low, assuming the emission durations equal (t 1 = t 2 ) in the B=0 and B≠0 conditions.…”

The application of magnetic field at low pressure for optimal laser-induced plasma spectroscopy

“…There are additional factors such as resistivity or interaction with ambient gas that would prohibit the plasma to stop [19]. Thus equation (1) holds well if plasma is a fully conducting medium with no ambient gas [24]. Nevertheless it is reasonable to assume equation (1) for the relationship between the intensity and the magnetic field in the present investigation.…”

“…the additional factors of density fluctuation and high-frequency instability occurring where the plasma kinetic energy becomes equal to its magnetic energy may be also responsible for the presented reduction in the spectral intensities [24,25].…”

Theoretical aspect of enhancement and saturation in emission from laser produced plasma

“…Investigation of dynamics and emission from laser-produced plasma under different conditions (Dawson, 1964;Radziemski & Cremers, 1989;Batani, 2010;Schwarz et al, 2010;Kumar et al, 2010a;Kumar et al, 2010b;Krasa et al, 2011;Nath & Khare, 2011) is an important subject for many laboratories due to its technological application in various fields of research such as material science, chemical physics, plasma physics as well as inertial and magnetic confinement fusion (Chrisey & Hubler, 1994;Bauerle, 1996;Zel'Dovich & Raizer, 1966;Grun et al, 1981;Radziemski & Cremers, 1989;Rai et al, 1998;Doria et al, 2004;Borisenko et al, 2008;Hoffman, 2009;Wang et al, 2011;Kumar & Verma, 2011;Huber et al, 2011;Fazeli et al, 2011).…”