10.7910/DVN/0JOUCXJ.W. Hughes, P.B. Snyder, M.L. Reinke, B. LaBombard, S. Mordijck, S. Scott, E. Tolman, S.G. Baek, T. Golfinopoulos, R.S. Granetz, M. Greenwald, A.E. Hubbard, E. Marmar, J.E. Rice, A.E. White, D.G. Whyte, T. Wilks, S. WolfeHarvard Dataverse2018PhysicsAlcator C-Modconfinementh-modehigh fieldpedestal2018-10-031827978722337625605503724881533770620721424522346081138190931211358781139216953301380814040626156296331806620337312246673424952142337042656286418220160286418216048178829027904057320621010002377770application/pdfapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscriptapplication/x-hdf5application/postscript1.0Experiments on the Alcator C-Mod tokamak have utilized reactor-relevant magnetic fields to sustain substantially higher pedestal pressure than in other devices and allow close approach to the ITER H-mode baseline target pedestal pressure of 90 kPa. The EPED model, which couples the physics of transport driven by kinetic ballooning modes and MHD instabilities arising from peeling-ballooning modes, predicts the pressure profile at the onset of edge-localized modes (ELMs), and yields to lowest order a critical-βN like behavior for the pedestal: p∝Bt×Bp ( ∝Bt^2 for fixed edge q). C-Mod routinely accesses edge plasma pressure in excess of 30 kPa, often by using a high-density (ne>3×10^20 m^-3) approach to high confinement, taking advantage of a regime known as enhanced D-alpha (EDA) H-mode. In the EDA H-mode, plasma transport regulates both the pedestal profiles and the core impurity content, thus holding the pedestal stationary at just below the peeling-ballooning stability boundary. This stationary ELM-suppressed regime has approached the maximum pedestal predicted by EPED at these densities: 60 kPa. This in turn gives rise to volume-averaged core plasma pressure in excess of 0.2MPa, a world record value for a magnetic fusion device. Another approach to achieving high pressure utilizes a pedestal limited by current-driven modes at low collisionality, in which pressure increases with density and which allows access to a higher EPED solution, termed “super-H”. C-Mod experiments at reduced density (ne<2×10^20 m^-3) and strong plasma shaping (δ>0.5) accessed this regime, producing pedestals with pressures up to 80kPa (approximately 90% of the ITER target) and temperatures of nearly 2 keV. In a number of these hot H-modes, we observe strong edge instabilities at low toroidal mode number (n=1) when pedestal pressure approaches predicted values from EPED, showing that current-driven MHD modes can serve as a limit on the pedestal in a metal-walled tokamak at high pressure and low collisionality.<a href="http://library.psfc.mit.edu/catalog/reports/2010/18ja/18ja005/abstract.php">PSFC REPORT PSFC/JA-18-5</a><br /><br />Supported by U.S. Department of Energy awards DE-FC02-99ER54512, DE-FG02-95ER54309, DE-FC02-06ER54873, DE-AC02-09CH11466, DE-AC05-00OR22725, DE-SC0007880 using Alcator C-Mod, a DOE Office of Science User Facility.