Synchrotron emission in Alcator C-Mod: spectra at three magnetic fields, visible camera images, and polarization data

Alcator C-Modu0027s high magnetic field allows runaway electron synchrotron emission to be observed in the visible wavelength range. Visible spectrometers were used to measure synchrotron spectra at three magnetic fields: 2.7, 5.4, and 7.8 T. Both a test-particle model and kinetic solver CODE (COllisional Distribution of Electrons) explore the energy evolution of the runaway population and the impact of magnetic-field-dependent synchrotron radiation as a power loss mechanism. Additionally, distortion-corrected visible camera images capture the spatial distribution and evolution of synchrotron emission in C-Mod. Initial results show good agreement between experiment and the new synthetic diagnostic SOFT (Synchrotron-detecting Orbit-Following Toolkit). Finally, a first look at synchrotron polarization data is presented.