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Title	41: Investigation of the effects of the EHO toroidal mode number on the edge particle transport
Name:	Ahmed Diallo adiallo@pppl.gov	Affiliation:	Princeton Plasma Physics Laboratory
Research Area:	Inductive Scenarios	Presentation time:	Not requested
Co-Author(s):	K. Burrell, R. Maingi, A. Garofalo(?), E. Doyle(?), S. Gerhardt	ITPA Joint Experiment :	No
Description:	The goal of this proposal is to investigate the impact of the edge harmonic oscillation (EHO) characteristics (e.g., toroidal mode number n, and relative amplitude of each n-components, finite n-spectrum vs broadband) on the edge pedestal particle transport.	ITER IO Urgent Research Task :	No
Experimental Approach/Plan:	The experimental plan will utilize the established experimental parameters developed for the toroidal mode control of the EHO proposed by K. Burrell in ROF 14. Using similar experimental conditions to select the toroidal mode number dominant contribution of the EHOs, we will quantify the edge particle transport for various EHO characteristics. This quantification is to be performed using the following three approaches in order of priority. 1.The first approach will focus on non-recycling transport analysis induced by EHO. This approach will rely gas injection using silane (SiH4) or carbon tetrafluoride (CF4) to study the transport of non-recycling particles as a function of EHO n-spectrum. 2.The second approach will target the electron transport. This approach will reconstruct the pedestal density and temperature as a function of the multiple phases of the dominant magnetic signature of the EHO. The goal is to elucidate the relationship between particle and heat transport by providing fast reconstruction of the edge pedestal structure through the full cycle of the dominant mode in the magnetic signature of various types of EHOs. 3.Finally, the last approach will ??consider? a modulated gas puff (at rate near particle confinement time) to determine the edge transport parameters (particle diffusion coefficient D and pinch velocity v) for the dialed EHOs n spectrum. Note that this approach will be used in tandem with the fast reflectometer density prole measurements sampling the pedestal region for a complete characterization of the density fluctuations induced by the gas modulation. In addition, measurements of the density profile pedestal structure can be obtained from the fast reflectometry at each phase of the modulation of the gas puff. For completeness, this modulation experiment could in principle be repeated for obtaining the transport coefficients of impurities such as Helium.
Background:	The viability of ITER as a test fusion reactor hinges on achieving steady state edge particle transport for ELM avoidance. A potential scenario candidate is the quiescent H-Mode (QH) discovered on DIIID. Experiments have shown that EHO is a key ingredient in achieving QH mode. The EHO has been extensively studied in ITER relevant scenarios (low-torque) and a range of toroidal mode numbers have been shown to be associated with EHOs. In addition, EHO was shown to produce electron, main ion, and impurity particle transport at the plasma edge at a rapid rate compared to that produced by ELMs under similar conditions. However, no systematic investigations of the particle transport dependence on the toroidal mode spectrum characteristics has been performed to establish to optimum mode number and extrapolate to ITER conditions. The goal of this experiment is two-fold. First, we document the particle transport explicitly as a function of EHO toroidal mode content. Second, we identify the key physics mechanism for enhanced particle transport.
Resource Requirements:	Fast modulation of gas feed (Frequency TBD). Fast-sweeping reflectometer sampling the pedestal region. Impurity injection capability.
Diagnostic Requirements:	All profiles diagnostics. DBS measurements and reflectometry, BES large array centered on pedestal region, and calibrated midplane Dalpha signals to study the particle flux in EHOs.
Analysis Requirements:	--
Other Requirements:	--