Integrated Plasma Simulation of Lower Hybrid Current Drive Modification of Sawtooth*

It has been shown in Alcator C-Mod that the onset time for sawteeth can be delayed significantly (up to 0.5 s) relative to ohmically heated plasmas, through the injection of off-axis LH current drive power [1]. We are simulating these experiments using the Integrated Plasma Simulator (IPS) [2], through which driven current density profiles are computed using a ray tracing code (GENRAY) and Fokker Planck code (CQL3D) [3]. These modules are executed repeatedly as the background plasma is evolved using the TSC transport code with the Porcelli sawtooth model [4]. Predictions of the driven LH current profiles will be compared with simpler ``reduced'' models for LHCD such as the LSC code which is implemented in TSC. \\[4pt] [1] C. E. Kessel \textit{et al}, Bull. of the Am. Phys. Soc. \textbf{53}, Poster PP6.00074 (2008). \\[0pt] [2] D. Batchelor \textit{et al}, Journal of Physics: Conf. Series \textbf{125}, 012039 (2008). \\[0pt] [3] R. W. Harvey and M. G. McCoy, Proc. of the IAEA Tech. Comm. Meeting on Simulation and Modeling of Therm. Plasmas, Montreal, Canada (1992). \\[0pt] [4] S. C. Jardin \textit{et al}, J. Comp. Phys. \textbf{66}, 481 (1986).