Driving momentum evolution with magnetic topology GOAL Understand

Driving momentum evolution with magnetic topology • GOAL: Understand the transport of momentum into the core from the scrape-off layer (SOL). – Derive diffusion and convection coefficients – Keep energy confinement constant • It has been shown flows change direction in the SOL when magnetic topology is changed. Edge SOL Boron velocity r/a ~ 1. 07

Temporal Evolution of Momentum 2 shots: Core Ar velocity • Rapid changes to the magnetic topology during a shot appear to provide impulses of momentum that would propagate inward. • Ssep is the distance between the primary and secondary separatrices mapped to the outboard midplane. J. Rice – Ideas Forum 2005

Needs • Evolution of the momentum profile at the inner (r/a ~ 0. 93 to 1. 04) and outer edges (r/a ~ 0. 86 to 1. 06, poloidal only at outer edge) would be measured with GPI and DNB viewing fibers. – We would prefer the full velocity diagnostic suite (probes, Hirex Jr. , Ne. So. X) active for this run to share discharges. – Try to keep energy confinement constant, so no RF heating needed. • Sweep from LSN to USN as well as USN to LSN to provide momentum change. – Significant control of the magnetic topology would be required to sweep ssep fast enough (~50 ms or better? ) to create a momentum ‘pulse. ’ • A few shots for each sweep direction at a few currents would fill half a run day, provide some repeatability, and explore temperature dependencies. – nl_04 ~ 1. 0 – Ip ~ 0. 8 MA – 1. 2 MA