ECRH/EBWH system for NSTX-U

Taylor, G.; Ellis, R.; Harvey, R. W.; Hosea, J.; Смирнов, А. П.

doi:10.1051/epjconf/20123202014

Cited by 9 publications

(11 citation statements)

References 11 publications

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“…3(b)). Earlier GENRAY simulations of EC heating of a B T (0) = 0.5 T NSTX CHI discharge predicted a first pass absorption of up to 25% at T e (0) = 10 eV and 65% at T e (0) = 100 eV [17].…”

Section: Ec Heating Results For a Chi Start-up Dischargesmentioning

confidence: 94%

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Physics design of a 28 GHz electron heating system for the National Spherical Torus experiment upgrade

Taylor

Bertelli

Ellis

et al. 2014

AIP Conference Proceedings

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Abstract.A megawatt-level, 28 GHz electron heating system is being designed to support non-inductive (NI) plasma current (I p ) start-up and local heating and current drive (CD) in H-mode discharges in the National Spherical Torus Experiment Upgrade (NSTX-U). The development of fully NI I p start-up and ramp-up is an important goal of the NSTX-U research program. 28 GHz electron cyclotron (EC) heating is predicted to rapidly increase the central electron temperature (T e (0)) of low density NI plasmas generated by Coaxial Helicity Injection (CHI). The increased T e (0) will significantly reduce the I p decay rate of CHI plasmas, allowing the coupling of fast wave heating and neutral beam injection. Also 28 GHz electron Bernstein wave (EBW) heating and CD can be used during the I p flat top in NSTX-U discharges when the plasma is overdense. Ray tracing and Fokker-Planck numerical simulation codes have been used to model EC and EBW heating and CD in NSTX-U. This paper presents a pre-conceptual design for the 28 GHz heating system and some of the results from the numerical simulations.

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“…3(b)). Earlier GENRAY simulations of EC heating of a B T (0) = 0.5 T NSTX CHI discharge predicted a first pass absorption of up to 25% at T e (0) = 10 eV and 65% at T e (0) = 100 eV [17].…”

Section: Ec Heating Results For a Chi Start-up Dischargesmentioning

confidence: 94%

“…The density and temperature profiles used for this case are shown in Fig. 5(a) of [17]. The maximum O-X-B mode conversion efficiency was obtained at a parallel launch wavenumber, n // = ± 0.7.…”

Section: Ebw Heating and Current Drive Results For A Nstx-u H-mode DImentioning

confidence: 99%

Physics design of a 28 GHz electron heating system for the National Spherical Torus experiment upgrade

Taylor

Bertelli

Ellis

et al. 2014

AIP Conference Proceedings

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“…A megawatt-level 28 GHz electron cyclotron heating system is currently planned as an upgrade in NSTX-U in 2017-18 [40,41]. The gyrotron can deliver up to 1 MW of power to the plasma over a pulse length of 1-5 s, which will be transmitted via a low-loss, corrugated HE 1, 1 waveguide [40,41].…”

Section: Electron Cyclotron Waves Heatingmentioning

confidence: 99%

Simulations towards the achievement of non-inductive current ramp-up and sustainment in the National Spherical Torus Experiment Upgrade

et al. 2015

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One of the goals of the National Spherical Torus Experiment Upgrade (NSTX-U) (Menard et al 2012 Nucl. Fusion 52 083015) is the demonstration of fully non-inductive start-up, current ramp-up and sustainment. This work discusses predictive simulations where the available heating and current drive systems are combined to maximize the non-inductive current and minimize the solenoidal contribution. Radio-frequency waves at harmonics higher than the ion cyclotron resonance (high-harmonic fast waves (HHFW)) and neutral beam injection are used to ramp the plasma current non-inductively starting from an initial Ohmic plasma. An interesting synergy is observed in the simulations between the HHFW and electron cyclotron (EC) wave heating. Time-dependent simulations indicate that, depending on the phasing of the HHFW antenna, EC wave heating can significantly increase the effectiveness of the radiofrequency power, by heating the electrons and increasing the current drive efficiency, thus relaxing the requirements on the level of HHFW power that needs to be absorbed in the core plasma to drive the same amount of fast-wave current.

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“…A megawatt-level 28 GHz EC heating system is planned for NSTX-U [8,11] and is expected to be operational in 2017-18. In NSTX-U at B T (0) = 1 T O-mode fundamental 28 GHz EC heating is resonant near the magnetic axis and the O-mode cut off is at n e ~ 10 19 m -3 , limiting EC heating to early in the I p ramp-up.…”

Section: Improving Fast Wave Heating During Start-up With Electron Cymentioning

confidence: 99%

Development of fully non-inductive plasmas heated by medium and high-harmonic fast waves in the national spherical torus experiment upgrade

Taylor

Poli

Bertelli

et al. 2015

AIP Conference Proceedings

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Abstract.A major challenge for spherical tokamak development is to start-up and ramp-up the plasma current (I p ) without using a central solenoid. Experiments in the National Spherical Torus eXperiment (NSTX) demonstrated that 1.4 MW of 30 MHz high-harmonic fast wave (HHFW) power could generate an I p = 300 kA H-mode discharge with a non-inductive I p fraction, f NI ~ 0.7. The discharge had an axial toroidal magnetic field (B T (0)) of 0.55 T, the maximum B T (0) available on NSTX. NSTX has undergone a major upgrade (NSTX-U), that will eventually allow the generation of B T (0) ≤ 1 T and I p ≤ 2 MA plasmas. Full wave simulations of 30 MHz HHFW and medium harmonic fast wave (MHFW) heating in NSTX-U predict significantly reduced FW power loss in the plasma edge at the higher B T (0) achievable in NSTX-U. HHFW experiments will aim to generate stable, f NI ~ 1, I p = 300 kA H-mode plasmas and to ramp I p from 250 to 400 kA with FW power. Time-dependent TRANSP simulations are used to develop non-inductive I p ramp-up and sustainment using 30 MHz FW power. This paper presents results from these RF simulations and plans for developing non-inductive plasmas heated by FW power.

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ECRH/EBWH system for NSTX-U

Cited by 9 publications

References 11 publications

Physics design of a 28 GHz electron heating system for the National Spherical Torus experiment upgrade

Physics design of a 28 GHz electron heating system for the National Spherical Torus experiment upgrade

Simulations towards the achievement of non-inductive current ramp-up and sustainment in the National Spherical Torus Experiment Upgrade

Development of fully non-inductive plasmas heated by medium and high-harmonic fast waves in the national spherical torus experiment upgrade

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