Toroidal asymmetry of divertor heat deposition in NSTX

2-D heat flux data calculated by a 3-D heat conduction solver allowed for the evaluation of peak heat flux (q$_{peak})$ and heat flux width ($\lambda _{q})$ for each toroidal angle, which generates a toroidal array of q$_{peak}$ and $\lambda _{q}$ at each time slice. Then the toroidal degree of asymmetry (DoA) of q$_{peak}$ and $\lambda _{q}$ as a function of time was defined as DoA(q$_{peak})=\sigma _{qpeak}$/mean(q$_{peak})$ and DoA($\lambda _{q})=\sigma _{\lambda q}$ /mean($\lambda _{q})$, where $\sigma $ is the standard deviation of q$_{peak}$ and $\lambda _{q}$ over data in the toroidal array. In case of ELMs and 3-D field application, the helical heat deposition produces additional scatter of data around mean values to the background scatter level without these events and it raises DoA for both q$_{peak}$ and $\lambda _{q}$. Both values of DoA(q$_{peak})$ and DoA($\lambda _{q})$ are highest at the ELM peak times, with DoA(q$_{peak})$ up to $\sim $0.9 and DoA($\lambda _{q})$ up to $\sim $0.3 for typical type-III ELMs, while they become lower toward the later stage of the inter-ELM period, \textit{eg}, DoA(q$_{peak})\sim $0.15 and DoA($\lambda _{q})\sim $0.05. The correlation between DoA(q$_{peak})$ and DoA($\lambda _{q})$ is the strongest at the ELM peak times and becomes weaker later in the ELM cycle.