Microwave and Millimeter-Wave Diagnostics Upgrades for LTX-$\beta$

Measurements of fluctuations and their relation to transport are of key interest in the LTX-$\beta$ device, which will feature higher $B_T$ and $I_P$, and neutral beam heating. Improvements are underway for the microwave and millimeter-wave diagnostics on LTX-$\beta$, with the goal of significantly enhancing the capabilities for fluctuation measurements. Currently, a 296 GHz single-chord interferometer provides radial line density measurements, while an FM-CW (frequency-modulated continuous-wave) reflectometer (13.5$-$33 GHz) provides fast density profile measurements. Additional hardware and data acquisition for these systems will provide both higher bandwidths and better noise rejection. Two new variable-frequency reflectometer channels with frequency ranges of 13$-$20 GHz and 27$-$40 GHz will provide quadrature measurements of edge and core electron density fluctuations. New data analysis techniques include using the FM-CW system as a correlation reflectometer for low-$k$ fluctuations near the cutoff layer, as well as a radial backscattering ($k_r$$\leq$16 cm$^{-1}$) system for fluctuations far from the cutoff, while the interferometer can function as a far-forward scattering system.