Study of Strong Magnetic Fields Using Parametric Instability in a Magnetised Plasma

Generation of strong magnetic fields with a strength of 10-50MG plays a key role in some recent conceptions for controlled fusion. We suggest a laser method for measuring the local magnetic field, B\textgreater 10MG, based on the parametric decay of the laser radiation to $\omega $/2 and 3/2$\omega $ harmonics which are generated in the area with the electron density of a quarter of the critical plasma density. Spectral components of parametric harmonics carry a signature of both the plasma temperature and strong magnetic field. A two-plasmon decay of laser radiation was studied in a magnetized plasma at the 1MA pulsed power Zebra facility at the University of Nevada, Reno. Dense magnetized plasma with a magnetic field of 1-3MG was created by the 1MA current flowing in the metal rod 0.7-2mm in diameter. Radiation from the narrowband laser with intensity \textgreater 10$^{14}$ W/cm$^{2}$ was focused on the surface plasma. Spectrum of the backscattering 3/2$\omega $ harmonic included ``red'' and ``blue'' shifted components. Large 2-3nm shifts of spectral components was identified with laser heating of plasma. Components with a small 0.1nm spectral shift of may be linked to the magnetic field.