TJ-II:Spectroscopy: Difference between revisions

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[[TJ-II]] disposes of an nine-channel, high-resolution, spectroscopic diagnostic system. This system is currently being used to measure impurity ion temperature and poloidal rotation using passive emission spectroscopy. The principal features of the diagnostic include independent focusing of its channels, high sensitivity for performing Doppler measurements in low-density [[TJ-II:Electron Cyclotron Resonant Heating|ECR-heated]] plasmas, as well as a flexible and fast in-house-developed software program for performing integrated data reduction and analysis.
== Multichannel system ==
<ref>[http://link.aip.org/link/?RSINAK/72/971/1 A. Baciero et al, ''A multi-channel spectroscopic system for measuring impurity ion temperatures and poloidal rotation velocities in TJ-II'', Rev. Sci. Instrum. '''72''' (2001) 971]</ref>
<ref>[http://www.new.ans.org/pubs/journals/fst/a_1264 B. Zurro et al, ''Comparison of Impurity Poloidal Rotation in ECRH and NBI Discharges of the TJ-II HELIAC'', Fusion Science and Technology '''50''', 3 (2006) 419-427]</ref>


Proton rotation has been measured using spectral line emission from excited fast neutrals created from inner core plasma protons via charge exchange transfer reactions.
[[Image:spectrometer-setup.png|frame|Observation geometry of the nine-channel high-resolution spectroscopic diagnostic system]]
<ref>[http://link.aip.org/link/?RSINAK/74/2056/1 B. Zurro et al, ''Investigation of proton rotation measurements using hydrogen line wings in the TJ-II stellarator'', Rev. Sci. Instrum. '''74''' (2003) 2056]</ref>


Another method for measuring absolutely calibrated rotation velocities consists of simultaneously recording the emission lines from the plasma and from a calibration lamp by means of a double fiber-fiber guide.
[[TJ-II]] disposes of a nine-channel, high-resolution, spectroscopic diagnostic system. This system is currently being used to measure [[impurities|impurity]] ion temperature and poloidal rotation using passive emission spectroscopy. The principal features of the diagnostic include independent focusing of its channels, high sensitivity for performing Doppler measurements in plasmas, as well as a flexible and fast in-house-developed software program for performing integrated data reduction and analysis.
<ref>[http://link.aip.org/link/?RSINAK/77/033506/1 D. Rapisarda et al, ''Novel passive spectroscopy system for absolutely referenced plasma rotation measurements in clean plasmas'', Rev. Sci. Instrum. '''77''' (2006) 033506]</ref>
<ref>A. Baciero et al, ''A multi-channel spectroscopic system for measuring impurity ion temperatures and poloidal rotation velocities in TJ-II'', [[doi:10.1063/1.1326008|Rev. Sci. Instrum. '''72''' (2001) 971]]</ref>
<ref>B. Zurro et al, ''Comparison of Impurity Poloidal Rotation in ECRH and NBI Discharges of the TJ-II HELIAC'', [http://www.new.ans.org/pubs/journals/fst/a_1264 Fusion Science and Technology '''50''', 3 (2006) 419-427]</ref>. This experimental system has also been used to measure proton rotation using spectral line emission from excited fast neutrals created from inner core plasma protons via charge exchange transfer reactions. <ref>B. Zurro et al, ''Investigation of proton rotation measurements using hydrogen line wings in the TJ-II stellarator'', [[doi:10.1063/1.1537035|Rev. Sci. Instrum. '''74''' (2003) 2056]]</ref>


A vacuum ultraviolet spectrometer is used for performing spectral surveys and specialized plasma studies.
== Toroidal rotation measurement ==
<ref>[http://link.aip.org/link/?RSINAK/70/312/1 K.J. McCarthy et al, ''A toroidal focusing mirror based vacuum ultraviolet diagnostic for TJ-II'', Rev. Sci. Instrum. '''70''' (1999) 312]</ref>
<ref>[http://link.aip.org/link/?APCPCS/1058/219/1 K.J. McCarthy et al, ''A Study of Spectral Lines in Plasmas Heated by Neutral Beam Injection in the TJ-II Stellarator'', AIP Conf. Proc. '''1058''' (2008) 219-221]</ref>


The chord-integrated emissions of spectral lines are  monitored by using a spectral system with time and space scanning capabilities and relative calibration over the entire UV-visible spectral range. This system has been used to study the line ratio of lines of different ionization stages of carbon C<sup>5+</sup> 5290 &Aring; and C<sup>4+</sup> 2271 &Aring; for plasma diagnostic purposes.  
[[File:TJ-II McPherson.jpg|300px|thumb|right|The VUV spectrometer on TJ-II]]
<ref>[http://link.aip.org/link/?RSINAK/79/10F540/1 B. Zurro et al, ''An experimental system for spectral line ratio measurements in the TJ-II stellarator'', Rev. Sci. Instrum. '''79''' (2008) 10F540]</ref>
A method for measuring absolutely calibrated toroidal rotation velocities consists of simultaneously recording the emission lines from the plasma and from a calibration lamp by means of a double fiber-fiber guide.
<ref>D. Rapisarda et al, ''Novel passive spectroscopy system for absolutely referenced plasma rotation measurements in clean plasmas'', [[doi:10.1063/1.2185507|Rev. Sci. Instrum. '''77''' (2006) 033506]]</ref>
The system has been mounted at &phi; = -9.45&deg; ([[TJ-II:Sectors|sector]] D8) and
&phi; = 170.56&deg; ([[TJ-II:Sectors|sector]] B8).
 
== VUV spectroscopy ==
 
A vacuum ultraviolet spectrometer has been operated on TJ-II since 1999. It is an f/10.4 1 m normal-incidence vacuum spectrometer equipped with interchangeable 1200 and 3600 lines mm<sup>-1</sup> gratings and a back-illuminated CCD camera with 400 &times; 1340 pixels (20 &times; 20 &mu;m<sup>2</sup>). The instrument covers the wavelength range from ~20 to ~300 nm. It has been used to perform spectral surveys (identify and follow the evolution of plasma [[impurities]]), to obtain impurity ion temperatures, and to perform specialized studies (e.g. study fast oxygen ions present in plasmas during the neutral beam injection heating phase).
<ref>K.J. McCarthy, B. Zurro, R. Balbín, A. Baciero, J. Herranz, and I. Pastor, ''Results of an experiment relating apparent Doppler ion temperatures with non-thermal velocities in hot-fusion plasmas'', [[doi:10.1209/epl/i2003-00476-x|Europhys. Lett. '''63''' (2003) 49]]</ref>
<ref>K.J. McCarthy, M. A. Ochando, F. Medina, B. Zurro, C. Hidalgo, M. A. Pedrosa, I. Pastor, J. Herranz and A. Baciero, ''A First Study of Impurity Behavior During Externally Induced Radial Electric Fields in the TJ-II Stellarator'', [http://www.new.ans.org/store/j_548 Fusion Sci. & Tech. '''46''', 129-134 (2004)]</ref>
<ref>K.J. McCarthy, V. Tribaldos, J. Arévalo, and M. Liniers, ''The detection of fast oxygen ions in neutral beam-heated plasmas of the TJ-II stellarator using spectroscopy methods'', [[doi:10.1088/0953-4075/43/14/144020|J. Physics B: Atomic, Molecular and Optical Physics '''43''' (2010) 144020]]</ref>
 
== Charge exchange recombination spectroscopy ==
 
The TJ-II is also equipped with a multi-channel spectroscopic and compact [[TJ-II:Diagnostic neutral beam|diagnostic neutral beam injector system]] optimized for performing [[TJ-II:Charge exchange spectroscopy|Charge Exchange Recombination Spectroscopy]]. It permits localized measurements of the [[impurities|impurity]] ion temperature as well as poloidal and toroidal velocity at 12 positions across the plasma minor radius. For this, the system is set-up to observe the 529.06 nm line emission of C<sup>+5</sup>.


== References ==
== References ==
<references />
<references />

Latest revision as of 17:20, 3 April 2018

Multichannel system

Observation geometry of the nine-channel high-resolution spectroscopic diagnostic system

TJ-II disposes of a nine-channel, high-resolution, spectroscopic diagnostic system. This system is currently being used to measure impurity ion temperature and poloidal rotation using passive emission spectroscopy. The principal features of the diagnostic include independent focusing of its channels, high sensitivity for performing Doppler measurements in plasmas, as well as a flexible and fast in-house-developed software program for performing integrated data reduction and analysis. [1] [2]. This experimental system has also been used to measure proton rotation using spectral line emission from excited fast neutrals created from inner core plasma protons via charge exchange transfer reactions. [3]

Toroidal rotation measurement

The VUV spectrometer on TJ-II

A method for measuring absolutely calibrated toroidal rotation velocities consists of simultaneously recording the emission lines from the plasma and from a calibration lamp by means of a double fiber-fiber guide. [4] The system has been mounted at φ = -9.45° (sector D8) and φ = 170.56° (sector B8).

VUV spectroscopy

A vacuum ultraviolet spectrometer has been operated on TJ-II since 1999. It is an f/10.4 1 m normal-incidence vacuum spectrometer equipped with interchangeable 1200 and 3600 lines mm-1 gratings and a back-illuminated CCD camera with 400 × 1340 pixels (20 × 20 μm2). The instrument covers the wavelength range from ~20 to ~300 nm. It has been used to perform spectral surveys (identify and follow the evolution of plasma impurities), to obtain impurity ion temperatures, and to perform specialized studies (e.g. study fast oxygen ions present in plasmas during the neutral beam injection heating phase). [5] [6] [7]

Charge exchange recombination spectroscopy

The TJ-II is also equipped with a multi-channel spectroscopic and compact diagnostic neutral beam injector system optimized for performing Charge Exchange Recombination Spectroscopy. It permits localized measurements of the impurity ion temperature as well as poloidal and toroidal velocity at 12 positions across the plasma minor radius. For this, the system is set-up to observe the 529.06 nm line emission of C+5.

References

  1. ↑ A. Baciero et al, A multi-channel spectroscopic system for measuring impurity ion temperatures and poloidal rotation velocities in TJ-II, Rev. Sci. Instrum. 72 (2001) 971
  2. ↑ B. Zurro et al, Comparison of Impurity Poloidal Rotation in ECRH and NBI Discharges of the TJ-II HELIAC, Fusion Science and Technology 50, 3 (2006) 419-427
  3. ↑ B. Zurro et al, Investigation of proton rotation measurements using hydrogen line wings in the TJ-II stellarator, Rev. Sci. Instrum. 74 (2003) 2056
  4. ↑ D. Rapisarda et al, Novel passive spectroscopy system for absolutely referenced plasma rotation measurements in clean plasmas, Rev. Sci. Instrum. 77 (2006) 033506
  5. ↑ K.J. McCarthy, B. Zurro, R. Balbín, A. Baciero, J. Herranz, and I. Pastor, Results of an experiment relating apparent Doppler ion temperatures with non-thermal velocities in hot-fusion plasmas, Europhys. Lett. 63 (2003) 49
  6. ↑ K.J. McCarthy, M. A. Ochando, F. Medina, B. Zurro, C. Hidalgo, M. A. Pedrosa, I. Pastor, J. Herranz and A. Baciero, A First Study of Impurity Behavior During Externally Induced Radial Electric Fields in the TJ-II Stellarator, Fusion Sci. & Tech. 46, 129-134 (2004)
  7. ↑ K.J. McCarthy, V. Tribaldos, J. Arévalo, and M. Liniers, The detection of fast oxygen ions in neutral beam-heated plasmas of the TJ-II stellarator using spectroscopy methods, J. Physics B: Atomic, Molecular and Optical Physics 43 (2010) 144020
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