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Plasma Initiation by Local Helicity Injection (LHI) on Pegasus-III

POSTER

Abstract

The Pegasus-III program is focused on developing the physics basis and predictive models for non-solenoidal tokamak startup. Local helicity injection (LHI) is a non-solenoidal tokamak startup technique utilizing localized current sources near the plasma edge. Electron beams injected into the vacuum magnetic field relax into a tokamak-like state, and drive toroidal current up to limits determined by either the helicity injection capability of the hardware or power balance. Several issues must be addressed before this technique is ready to deploy on a large facility including reliable operation with high LHI drive voltage, injector geometry optimization, gas control and minimization of impurity production. The LHI system on Pegasus-III features 4 discrete electron injectors near the outboard midplane capable of a total Iinj ≤ 16 kA and Vinj ≤ 1 kV, and a prototype non-circular injector capable of Iinj ≤ 8 kA and Vinj ≤ 500 V. A new Stark broadening diagnostic for arc fueling optimization and a new cathode spot detection system to minimize impurity injection and improve injector reliability are being deployed. These systems will facilitate investigation of the outstanding issues of LHI physics during the initial campaign of Pegasus-III.

Presenters

  • Aaron C Sontag

    University of Wisconsin-Madison, University of Wisconsin - Madison

Authors

  • Aaron C Sontag

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Molly W Aslin

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Michael W Bongard

    University of Wisconsin-Madison

  • Michael T Borchardt

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Stephanie J Diem

    University of Wisconsin - Madison, University of Wisconsin-Madison

  • Abigail L Ferris

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Raymond J Fonck

    University of Wisconsin - Madison, University of Wisconsin-Madison

  • Armand K Keyhani

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Benjamin A Kujak-Ford

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Benjamin T Lewicki

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Mark D Nornberg

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Jill K Peery

    University of Wisconsin - Madison

  • Christopher Pierren

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Joshua A Reusch

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Alexander T Rhodes

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Cuauhtemoc Rodriguez Sanchez

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Carolyn E Schaefer

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Timothy N Tierney

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Justin D Weberski

    University of Wisconsin-Madison, University of Wisconsin - Madison

  • Gregory R Winz

    University of Wisconsin-Madison, University of Wisconsin - Madison