Spectroscopic studies of plasma collapse in the Advanced Toroidal Facility

Isler, R.C.; Crume, E.C.; Horton, L.D.; Howe, H.C.; Voronov, G. S.

doi:10.1088/0029-5515/29/8/015

Cited by 11 publications

(10 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The behaviour of impurities and the role of radiation in this evolution are discussed in Ref. [3], where it is noted that once T e declines to a low level the plasmas become radiatively unstable, but it is not obvious that impurity radiation actually initiates the collapse. For the discharge shown in Fig.…”

Section: Evolution Of An Nbi Dischargementioning

confidence: 99%

“…By 283 ms, the electron temperature is low enough that C V intensity has a maximum in the plasma centre. The maxima in the radiation profiles for low ionization stages (N V, C IV) appear to remain localized at radii larger than 18 cm, but some ambiguities exist that are believed to be caused by strong poloidal asymmetries developing around the time of the energy collapse [3].…”

Section: Ion Temperature Profilesmentioning

confidence: 99%

See 1 more Smart Citation

Temperature behaviour during neutral beam injection in a torsatron (ATF) with field errors

Isler¹,

Horton²,

Voronov³

et al. 1989

Nucl. Fusion

View full text Add to dashboard Cite

Target plasmas for neutral beam injection (NBI) in the Advanced Toroidal Facility (ATF) are formed using approximately 200 kW of 53 GHz electron cyclotron heating (ECH). During the early operational period of this device, field errors existed which produced large islands at the ι = 1/2 surface and several smaller, but non-negligible closely spaced islands at larger radii. The evolution of typical plasma parameters during NBI into plasmas produced in this perturbed magnetic configuration is discussed. The ion temperatures near the centre of the ECH target plasmas, as measured from Doppler broadening of impurity lines, are approximately 100 eV, and the central electron temperatures are close to 800 eV. NBI at powers up to 1.4 MW characteristically raises Tj(O) by factors of two to three for 50−80 ms, but thereafter the ion temperature decays. The electron temperature is not raised by NBI above its level in the ECH plasmas; it typically drops monotonically from the start of injection. Both the Ti and the Te profiles indicate the existence of a low temperature region from the ι = 1/2 surface (ρ = 0.6) to the plasma edge, apparently because of the island structure, and modelling suggests that the plasma collapse may be caused by the peculiar radiation profile which develops under these conditions. However, whether the characteristics of the temperature profiles and the collapse can truly be ascribed to the existence of the islands can be decided only after repair of the field errors.

show abstract

Section: Evolution Of An Nbi Dischargementioning

confidence: 99%

Section: Ion Temperature Profilesmentioning

confidence: 99%

Temperature behaviour during neutral beam injection in a torsatron (ATF) with field errors

Isler¹,

Horton²,

Voronov³

et al. 1989

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

“…However, through improvements in wall conditioning (titanium gettering) and gas programming, collapse-free discharges with 250 ms of 1. [4]. The sharp peak in the O VI signal occurring 20-30 ms after the collapse is due to a thermal instability of the cooled plasma, which leads tc the final density decay.…”

Section: Plasma Performancementioning

confidence: 97%

Studies of plasma performance and transport in the advanced toroidal facility (ATF)

Neilson

Aceto

Anabitarte

et al. 1989

IEEE Thirteenth Symposium on Fusion Engineering

Self Cite

View full text Add to dashboard Cite

An overview of recent ATF experimental results and program plans is presented, with emphasis on the role of magnetic configuration controls in transport studies. The ATF operating space is bounded by a density limit that effectively sets a limit on the energy confinement time r£. Although this limit is not solely due to impurities, it has recently been raised by improved cleanliness following titanium gettering. This has led to collapse-free neutral beam injection (NBI) discharges with global T E % 16 ms. Preliminary experiments show that stored energy and bootstrap current are sensitive to details of the magnetic configuration.

show abstract

“…1 . 2 The ATF facility and its operational characteristics are described in detail in Ref. 3; only the pumping, baking, glow discharge, and gettering systems for the vacuum vessel are described here.…”

Section: Introductionmentioning

confidence: 99%