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FY2015 NSTX-U Facility and Diagnostic Milestones

F(15-1): Complete high-Z tile design and begin procurement.

For future facilities such as FNSF, it is important to investigate the viability of high-Z metallic divertor in NSTX-U. After making an assessment of all graphite PFC plasma operations, a row of high-Z tiles will be installed in the lower outboard divertor region.

F(15-2): Develop cryo-pump system engineering design.

For steady-state NSTX-U operations, an effective particle control tool is required. The divertor cryo-pump (DCP) has been used widely in conventional tokamak operations including DIII-D. On NSTX-U, a physics design study was performed on a closed divertor cryo-pump system in collaboration with ORNL. The initial indications are promising for providing divertor pumping for a relatively broad divertor parameter space including the snow-flake configuration. The cryo-pump system is a high priority major enhancement for the NSTX-U Five Year Plan. It is critical to develop an engineering design to start long-lead time procurements. The DCP is planned to be installed in mid-FY 2017, where a long torus outage (LTO) is planned to start.

F(15-3): Develop electron cyclotron heating (ECH) system engineering design.

ECH/EBW is a promising tool to initiate plasmas in STs and tokamaks without a central solenoid. It could also provide a means to control the plasma current profile. For NSTX-U, initially the ECH/EBW system will provide electron heating during non-inductive plasma start-up; later it will be used for off-axis EBW heating and current drive. The ECH system is a high priority major enhancement for the NSTX-U Five Year Plan. A 28 GHz high-power electron cyclotron/electron Bernstein wave (EC/EBW) heating system is planned in collaboration with the Tsukuba University, Japan. The engineering design includes a site-specific plan for the gyroton location and power supply/control. The initiation of procurement of the 28 GHz tube is a high priority because of the long manufacturing and qualification testing time. The ECH system is planned to be operational in FY 2017.

F(15-4): Develop non-axi-symmetric control coil (NCC) system engineering design.

NCC is a promising tool for NSTX-U MHD studies including improved control of RWMs, ELMs, and disruptions. This effort is in collaboration with Columbia University and General Atomics. The NCC system is a high priority major enhancement for the NSTX-U Five Year Plan. The engineering design includes the specification of the NCC coil configuration, back-plate (if any), and possible PFC modifications.

D(15-1): Install and commission Material Analysis Particle Probe (MAPP)

To support boundary physics operation, the MAPP diagnostic system will be installed and commissioned. MAPP is an in-vacuo inter-shot diagnostic capable of correlating surface chemistry evolution with plasma response to PMI conditioning. A unique MAPP capability is in-situ, between-shots sample analysis following plasma exposure, where samples are retracted in-vacuo into an adjoining chamber and a variety of analysis techniques are performed in-between shots.