A Pockels cell enabled heterodyne phase contrast imaging diagnostic for detection of ion cyclotron emission.

This work describes a novel optical heterodyne detection scheme that significantly extends the frequency response of the phase contrast imaging method to detect electron density fluctuations in tens of megahertz frequency range. The system employs a variable frequency electro-optic modulator to allow operation at any frequency in the range 10-40 MHz without the need to realign the system. The frequency coverage of the system makes it suitable to measure the radial structure of the electron density component of ion cyclotron emission on devices having confining magnetic field of a few tesla, thus extending the purely temporal measurements provided so far by magnetic probes.

A combined phase contrast imaging and heterodyne interferometer system for multiscale fluctuation measurements (invited).

In this work, a novel combined diagnostic capable of measuring multiscale density fluctuations that extend from magnetohydrodynamic (MHD) to the lower range of electron temperature gradient turbulence has been designed, installed, and operated at DIII-D. The combined diagnostic was constructed by adding a heterodyne interferometer to the pre-existing phase contrast imaging (PCI) system, both of which measure line-integrated electron density fluctuations. The port-space footprint is minimized via use of a single 10.6 µm probe beam. With temporal bandwidths in excess of 1 MHz, the PCI measures high-k (1.5 cm-1 < |k R | ≤ 25 cm-1) fluctuations with sensitivity 3 × 1 0 13 m - 2 / kHz , while the interferometer simultaneously measures low-k (|k R | < 5 cm-1) fluctuations with sensitivity 3 × 1 0 14 m - 2 / kHz . The intentional mid-k overlap has been empirically verified with sound-wave calibrations and allows quantitative investigation of multiscale effects that are predicted to be significant in the reactor-relevant T e ∼ T i regime. Furthermore, via correlation with the primary DIII-D interferometer, the toroidal mode numbers of core-localized MHD can be measured.

A phase contrast imaging-interferometer system for detection of multiscale electron density fluctuations on DIII-D.

Heterodyne interferometry and phase contrast imaging (PCI) are robust, mature techniques for measuring low-k and high-k electron density fluctuations, respectively. This work describes the first-ever implementation of a combined PCI-interferometer. The combined system uses a single 10.6 µm probe beam, two interference schemes, and two detectors to measure electron density fluctuations at large spatiotemporal bandwidth (10 kHz

Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic.

A novel rotating mask system has been designed and implemented on the DIII-D phase contrast imaging (PCI) diagnostic to produce the first spatially localized PCI measurements of a tokamak plasma. The localization technique makes use of the variation in the magnetic field component perpendicular to the viewing chord as a function of chord height. This new capability provides measurements in the range of 2

Leadership: a new conception.

The article summarizes the common wisdom regarding leadership that informs our present understanding of leadership. It articulates a new understanding of leadership, referred to as the postindustrial paradigm of leadership; comments on this new paradigm; contrasts it with the industrial paradigm of leadership; and ends with some comments on leadership as an episodic affair.