The relationship between Raman spectra and crystallographic orientation was examined for single crystals of Fo 89 Fa 11 olivine [(Mg 0.89 Fe 0.11 ) 2 SiO 4 ]. Raman spectra were obtained for chemically homogeneous olivine grains with various orientations on a thin section of mantle-derived rock (dunite) using micro-Raman equipment and an unpolarized exciting laser. Crystallographic orientations of each olivine grain were determined using an electron backscattered diffraction (EBSD) method. Five apparent peaks at 822 (peak 1), 854 (peak 2), 880 (peak 3), 917 (peak 4), and 959 cm −1 (peak 5) were observed in the spectral range of 700-1050 cm −1 . Intensity ratios of peak i to peak 2, I i /I 2 , for i = 1, 4, and 5 were formulated empirically as functions of crystallographic orientations: I i /I 2 = .a 1i q 2 /p 2 + a 2i q/p + a 3i / sin 2 f + .b 1i q 2 /p 2 + b 2i q/p + b 3i / sin f + c i where a 1i , a 2i , a 3i , b 1i , b 2i , b 3i , c i are constants. f is the angle between the [100] axis and the incident direction of the laser, and q is the angle between the [001] axis and the incident direction of laser projected on the f100g plane. These equations well describe the relationships between I i /I 2 and crystallographic orientation. The obtained empirical equations enable Raman spectroscopic determination of the crystallographic orientation of olivine.

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The n = 2 rotational instability is the most dangerous gross instability in a field-reversed theta pinch. It is demonstrated for the first time that the instability is completely suppressed by superposing a quadrupole field which is much smaller than the axial confinement field at the separatrix. The experimental threshold intensity of the field for stabilization is about 2.5 times less than that predicted by theoretical stability analysis.

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