  We describe the design of a Thomson scattering (TS) diagnostic to be used on
the SMall Aspect Ratio Tokamak (SMART). SMART is a spherical tokamak being
commissioned in Spain that aims to explore positive triangularity (PT) and
negative triangularity (NT) plasma scenarios at a low aspect ratio. The SMART
TS diagnostic is designed to enable a wide range of electron temperature (1 eV
to 1 keV) and density (0.5 - 10 $\times 10^{19} ~\rm{m^{ - 3}}$) measurements.
A 2Joule laser operating at 1064 nm will be used to probe the electron
temperature and density of the plasma. The laser is capable of operating in the
burst mode at 1kHz, 2kHz, and 4kHz to investigate fast phenomena or at $30$ Hz
to study 1 sec (or more) long discharges. The scattered light will be collected
over an angular range of 60-120 degrees at 28 spatial points in the midplane
covering the core region and edge plasma on both the low-field side (LFS) and
the high-field side (HFS). Simulation data is used to determine the optimum
location of Thomson scattering measurement points to effectively resolve the
edge pedestal in the LFS and HFS regions under different triangularity
conditions. Each scattering signal will be spectrally resolved on five
wavelength channels of a polychromator to obtain the electron temperature
measurement. We will also present a method to monitor in-situ laser alignment
in the core during calibrations and plasma operations.
