New physics capabilities from the upgraded Thomson scattering diagnostic on MAST

K. J. Gibson; N. Barratt; I. Chapman; N. Conway; M. R. Dunstan; A. R. Field; L. Garzotti; A. Kirk; B. Lloyd; H. Meyer; G. Naylor; T. O'Gorman; R. Scannell; S. Shibaev; J. Snape; G. J. Tallents; D. Temple; A. Thornton; S. Pinches; M. Valovic; M. J. Walsh; H. R. Wilson

doi:10.1088/0741-3335/52/12/124041

New physics capabilities from the upgraded Thomson scattering diagnostic on MAST

K. J. Gibson
, N. Barratt
, I. Chapman
, N. Conway
, M. R. Dunstan
, A. R. Field
, L. Garzotti
, A. Kirk
, B. Lloyd
, H. Meyer
, G. Naylor
, T. O'Gorman
, R. Scannell
, S. Shibaev
, J. Snape
, G. J. Tallents
, D. Temple
, A. Thornton
, S. Pinches
, M. Valovic

M. J. Walsh, H. R. Wilson

Research output: Contribution to journal › Article › peer-review

28 Scopus citations

Abstract

The newly upgraded MASTT homson scattering (TS) system provides excellent spatial resolution (̃1 cm) at over 130 radial locations across a full plasma diameter, and utilizes eight individual Nd: :YAG laser systems which can be fired sequentially, providing electron temperature and density profiles approximately every 4ms throughout a plasma discharge. By operating the system in burst mode, whereby the laser separation can be adjusted to within a few microseconds of each other, it is possible to obtain detailed profiles of transient and periodic phenomena such as sawteeth crashes, massive gas injection for disruption mitigation and the temperature perturbations associated with neoclassical tearing mode (NTM) islands. Following Fitzpatrick et al (1995 Phys. Plasmas 2 825), we consider a simplified model in which finite parallel diffusive heat transport can provide a threshold for NTM island growth and demonstrate that the TS derived electron temperature profiles around an island can be used to obtain both the island width and the critical island width belowwhich temperature gradients are maintained across the island, potentially removing the bootstrap current drive for the NTM. Initial results from high beta, neutral beam injection heated discharges on MAST show that the measured island width inferred from the TS data is in good agreement with magnetic estimates of the island width (considering both a cylindrical approximation and using a full field line tracing estimate). The temporal behaviour of the island width obtained from the magnetic diagnostics indicates that for the scenarios

Original language	English
Article number	124041
Journal	Plasma Physics and Controlled Fusion
Volume	52
Issue number	12
DOIs	https://doi.org/10.1088/0741-3335/52/12/124041
State	Published - Dec 2010
Externally published	Yes

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Gibson, K. J., Barratt, N., Chapman, I., Conway, N., Dunstan, M. R., Field, A. R., Garzotti, L., Kirk, A., Lloyd, B., Meyer, H., Naylor, G., O'Gorman, T., Scannell, R., Shibaev, S., Snape, J., Tallents, G. J., Temple, D., Thornton, A., Pinches, S., ... Wilson, H. R. (2010). New physics capabilities from the upgraded Thomson scattering diagnostic on MAST. Plasma Physics and Controlled Fusion, 52(12), Article 124041. https://doi.org/10.1088/0741-3335/52/12/124041

@article{d507ffe39ab7408e9ce36a70ee87b16b,

title = "New physics capabilities from the upgraded Thomson scattering diagnostic on MAST",

abstract = "The newly upgraded MASTT homson scattering (TS) system provides excellent spatial resolution {\~(}1 cm) at over 130 radial locations across a full plasma diameter, and utilizes eight individual Nd: :YAG laser systems which can be fired sequentially, providing electron temperature and density profiles approximately every 4ms throughout a plasma discharge. By operating the system in burst mode, whereby the laser separation can be adjusted to within a few microseconds of each other, it is possible to obtain detailed profiles of transient and periodic phenomena such as sawteeth crashes, massive gas injection for disruption mitigation and the temperature perturbations associated with neoclassical tearing mode (NTM) islands. Following Fitzpatrick et al (1995 Phys. Plasmas 2 825), we consider a simplified model in which finite parallel diffusive heat transport can provide a threshold for NTM island growth and demonstrate that the TS derived electron temperature profiles around an island can be used to obtain both the island width and the critical island width belowwhich temperature gradients are maintained across the island, potentially removing the bootstrap current drive for the NTM. Initial results from high beta, neutral beam injection heated discharges on MAST show that the measured island width inferred from the TS data is in good agreement with magnetic estimates of the island width (considering both a cylindrical approximation and using a full field line tracing estimate). The temporal behaviour of the island width obtained from the magnetic diagnostics indicates that for the scenarios",

author = "Gibson, \{K. J.\} and N. Barratt and I. Chapman and N. Conway and Dunstan, \{M. R.\} and Field, \{A. R.\} and L. Garzotti and A. Kirk and B. Lloyd and H. Meyer and G. Naylor and T. O'Gorman and R. Scannell and S. Shibaev and J. Snape and Tallents, \{G. J.\} and D. Temple and A. Thornton and S. Pinches and M. Valovic and Walsh, \{M. J.\} and Wilson, \{H. R.\}",

year = "2010",

month = dec,

doi = "10.1088/0741-3335/52/12/124041",

language = "English",

volume = "52",

journal = "Plasma Physics and Controlled Fusion",

issn = "0741-3335",

publisher = "IOP Publishing",

number = "12",

}

Gibson, KJ, Barratt, N, Chapman, I, Conway, N, Dunstan, MR, Field, AR, Garzotti, L, Kirk, A, Lloyd, B, Meyer, H, Naylor, G, O'Gorman, T, Scannell, R, Shibaev, S, Snape, J, Tallents, GJ, Temple, D, Thornton, A, Pinches, S, Valovic, M, Walsh, MJ & Wilson, HR 2010, 'New physics capabilities from the upgraded Thomson scattering diagnostic on MAST', Plasma Physics and Controlled Fusion, vol. 52, no. 12, 124041. https://doi.org/10.1088/0741-3335/52/12/124041

TY - JOUR

T1 - New physics capabilities from the upgraded Thomson scattering diagnostic on MAST

AU - Gibson, K. J.

AU - Barratt, N.

AU - Chapman, I.

AU - Conway, N.

AU - Dunstan, M. R.

AU - Field, A. R.

AU - Garzotti, L.

AU - Kirk, A.

AU - Lloyd, B.

AU - Meyer, H.

AU - Naylor, G.

AU - O'Gorman, T.

AU - Scannell, R.

AU - Shibaev, S.

AU - Snape, J.

AU - Tallents, G. J.

AU - Temple, D.

AU - Thornton, A.

AU - Pinches, S.

AU - Valovic, M.

AU - Walsh, M. J.

AU - Wilson, H. R.

PY - 2010/12

Y1 - 2010/12

N2 - The newly upgraded MASTT homson scattering (TS) system provides excellent spatial resolution (̃1 cm) at over 130 radial locations across a full plasma diameter, and utilizes eight individual Nd: :YAG laser systems which can be fired sequentially, providing electron temperature and density profiles approximately every 4ms throughout a plasma discharge. By operating the system in burst mode, whereby the laser separation can be adjusted to within a few microseconds of each other, it is possible to obtain detailed profiles of transient and periodic phenomena such as sawteeth crashes, massive gas injection for disruption mitigation and the temperature perturbations associated with neoclassical tearing mode (NTM) islands. Following Fitzpatrick et al (1995 Phys. Plasmas 2 825), we consider a simplified model in which finite parallel diffusive heat transport can provide a threshold for NTM island growth and demonstrate that the TS derived electron temperature profiles around an island can be used to obtain both the island width and the critical island width belowwhich temperature gradients are maintained across the island, potentially removing the bootstrap current drive for the NTM. Initial results from high beta, neutral beam injection heated discharges on MAST show that the measured island width inferred from the TS data is in good agreement with magnetic estimates of the island width (considering both a cylindrical approximation and using a full field line tracing estimate). The temporal behaviour of the island width obtained from the magnetic diagnostics indicates that for the scenarios

AB - The newly upgraded MASTT homson scattering (TS) system provides excellent spatial resolution (̃1 cm) at over 130 radial locations across a full plasma diameter, and utilizes eight individual Nd: :YAG laser systems which can be fired sequentially, providing electron temperature and density profiles approximately every 4ms throughout a plasma discharge. By operating the system in burst mode, whereby the laser separation can be adjusted to within a few microseconds of each other, it is possible to obtain detailed profiles of transient and periodic phenomena such as sawteeth crashes, massive gas injection for disruption mitigation and the temperature perturbations associated with neoclassical tearing mode (NTM) islands. Following Fitzpatrick et al (1995 Phys. Plasmas 2 825), we consider a simplified model in which finite parallel diffusive heat transport can provide a threshold for NTM island growth and demonstrate that the TS derived electron temperature profiles around an island can be used to obtain both the island width and the critical island width belowwhich temperature gradients are maintained across the island, potentially removing the bootstrap current drive for the NTM. Initial results from high beta, neutral beam injection heated discharges on MAST show that the measured island width inferred from the TS data is in good agreement with magnetic estimates of the island width (considering both a cylindrical approximation and using a full field line tracing estimate). The temporal behaviour of the island width obtained from the magnetic diagnostics indicates that for the scenarios

UR - https://www.scopus.com/pages/publications/78650020091

U2 - 10.1088/0741-3335/52/12/124041

DO - 10.1088/0741-3335/52/12/124041

M3 - Article

AN - SCOPUS:78650020091

SN - 0741-3335

VL - 52

JO - Plasma Physics and Controlled Fusion

JF - Plasma Physics and Controlled Fusion

IS - 12

M1 - 124041

ER -

New physics capabilities from the upgraded Thomson scattering diagnostic on MAST

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