Perpendicular to the beam path, there exist a number of optical ports for viewing the plasma at different radial positions. For a given plasma discharge, a fiber bundle system is placed on one of these ports, and is used to collect emission along its line-of-sight (black tubes on top of the machine contain light collection optics; fibers are placed in the long, curved white tube when not in use). This emission is sent to a spectrometer (located in big purple box), where it is dispersed over a finite wavelength range — which is centered on the emission line of interest — by a pair of optical gratings. However, because the collected emission is dominated by radiation from along the beam path, the measurements are effectively localized to the intersection volume between the fiber view and the beam. On MST, this intersection volume is small (~ 2 cm3) compared to the plasma volume, allowing spatially resolved measurements of "T"i and "v"i to be obtained. Data collected from a number of plasma discharges — for which the location of the fiber bundle system is varied — are used to construct radial profiles of the impurity ion temperature and velocity, providing important information for understanding the physics of plasmas in MST. Typical ion temperatures measured by CHERS on MST are in the range of 100 to 800 eV (2 million to 17 million degrees Fahrenheit), depending on position in the plasma and type of discharge. Likewise, measured equilibrium ion velocities are on the order of 1,000 to 10,000 meters per second.