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We measured concentrations of the two cosmogenic nuclides 32P and 7Be and radiogenic 234Th in the Southern California Bight during June and October 1989 in water depths up to 80 m. The depth of the mixed layer was 18 and 28 m, respectively, and the thermocline was well developed. The depth profiles of 32P are similar to an earlier profile in September 1987 but the column inventories are ∼5 times lower. 32P activity is fairly uniform in the mixed layer and decreases monotonically with depth below it. On the other hand, 7Be concentrations are nearly uniform to depths of 60–80 m. The integrated inventories of both dissolved 32P and 7Be are appreciably lower, by factors of 5–10, than their expected secular equilibrium concentrations for their mean oceanic injection rates. We show that the low inventories of 32P and 7Be are not due primarily to their decreased injection rates but rather to vertical mixing. The vertical eddy diffusivity and the consequent sustained new production based on upward NO3‒ fluxes have been estimated as >7 cm s and ∼1 g C m‒2 d‒1 from the observed profiles of 7Be, 32P, and NO3‒.

Using laser induced fluorescence (LIF), radial profiles of azimuthal ion fluid velocity and ion temperature are measured in the controlled shear de-correlation experiment (CSDX) linear helicon plasma device. Ion velocities and temperatures are derived from the measured Doppler broadened velocity distribution functions of argon ions. The LIF system employs a portable, high power (>300 mW), narrowband (∼1 MHz) tunable diode laser-based system operating at 668.614 nm. Previous studies in CSDX have shown the existence of a radially sheared azimuthal flow as measured with time delay estimation methods and Mach probes. Here, we report the first LIF measurements of sheared plasma fluid flow in CSDX. Above a critical magnetic field, the ion fluid flow profile evolves from radially uniform to peaked on axis with a distinct reversed flow region at the boundary, indicating the development of a sheared azimuthal flow. Simultaneously, the ion temperature also evolves from a radially uniform profile to a profile with a gradient. Measurements in turbulent and coherent drift wave mode dominated plasmas are compared.