Citation Lin, L. et al. " Studies of turbulence and transport in Alcator C-Mod H-mode plasmas with phase contrast imaging and comparisons with GYRO. Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. The MIT Faculty has made this article openly available. Please share how this access ...

The distinctive features of the ion gyro-harmonic discrete structures in narrowband stimulated electromagnetic emission (NSEE) spectra (within ±1 kHz heater frequency), excited by an extraordinary (X-mode) polarized high frequency (HF) pump wave F-region latitude ionosphere, are reported. Results were obtained from three sets experiments at EISCAT (European incoherent Scatter) HF Heating facili...

A relativistic bounce-averaged quasilinear diffusion equation is derived to describe stochastic particle transport associated with arbitrary-frequency electromagnetic fluctuations in a nonuniform magnetized plasma. Expressions for the elements of a relativistic quasilinear diffusion tensor are calculated explicitly for magnetically-trapped particle distributions in axisymmetric magnetic geometr...

Deterministic errors in angular rate gyros, such as thermal biases, can have a significant impact on spacecraft attitude knowledge. In particular, thermal biases are often the dominant error source in MEMS gyros after calibration. Filters, such as MEKFs, are commonly used to mitigate the impact of gyro errors and gyro noise on spacecraft closed loop pointing accuracy, but often have difficulty ...

An experimental study of picosecond pulse amplification in a gyrotron-traveling wave tube (gyro-TWT) has been carried out. The gyro-TWT operates with 30 dB of small signal gain near 140 GHz in the HE₀₆ mode of a confocal waveguide. Picosecond pulses show broadening and transit time delay due to two distinct effects: the frequency dependence of the group velocity near cutoff and gain narrowing b...

In preparation for the Hubble Space Telescope (HST) entry into Two Gyro Mode (TGM) operations, the NICMOS coronagraphic performance was assessed during the February 21, 2005 TGM on orbit test (ID: 10448) in two filter bands (F110W and F160W). The gyroscope pair 2-4 was used for the TGM test. Observations were obtained of a previously observed calibration target (GJ517; sp.type=K5Ve) coronagraph...

The paper pertains to the reduction of measurement errors in gyroscopes used for tracking the position of walking persons. Such tracking systems commonly use inertial or other means to measure distance traveled, and one or more gyros to measure changes in heading. MEMS-type gyros or IMUs are best suited for this task because of their small size and low weight. However, these gyros have large dr...

An inertial navigation system (INS) has been widely used in challenging GPS environments. With the rapid development of modern physics, an atomic gyroscope will come into use in the near future with a predicted accuracy of 5 × 10(-6)°/h or better. However, existing calibration methods and devices can not satisfy the accuracy requirements of future ultra-high accuracy inertial sensors. In this p...

The quaternion estimation (QUEST) batch attitude determination algorithm has been extended to work in a general Kalman-filter framework. This has been done in order to allow the inclusion of a complicated dynamics model and to allow the estimation of additional quantities beyond the attitude quaternion. The QUEST algorithm, which works with vector attitude observations, serves as a starting poi...

The traditional approach of star tracker for determining the centroid of spot requires enough energy and good shape, so a relatively long exposure time and stable three-axis state become necessary conditions to maintain high accuracy, these limit its update rate and dynamic performance. In view of these issues, this paper presents an approach for determining the centroid of star spot which base...