TJ-II:Charge exchange spectroscopy: Difference between revisions

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At [[TJ-II]], the ion temperature profile has been measured using a charge exchange neutral particle analyser (CX-NPA/Acord-12). The CX-NPA gives the energy spectrum of plasma ions at one point per shot, and the ion temperature can be calculated from this spectrum assuming a Maxwellian energy distribution function. The analyser can perform a poloidal scan covering a low magnetic field section at constant toroidal angle near &phi; = 175&deg;. Moreover, the particle flux is collimated in order that the tested plasma volume is small (the diameter is about 10 mm on magnetic axis). Due to the geometry of the device, the collected particle beam is very narrow and positioned almost perpendicular to magnetic field, therefore, the pitch of the collected particles is very small, tan<sup>-1</sup>(v<sub> ||</sub>/v<sub>per</sub>) &le; 3.1·10<sup>–2</sup> rad, which means that only the perpendicular velocity of trapped particles is measured. A radial profile is obtained using a series of reproducible discharges.
At [[TJ-II]], the ion temperature profile has been measured using a charge exchange neutral particle analyser (CX-NPA/Acord-12). The CX-NPA gives the energy spectrum of plasma ions at one point per shot, and the ion temperature can be calculated from this spectrum assuming a Maxwellian energy distribution function. The analyser can perform a poloidal scan covering a low magnetic field section at constant toroidal angle near &phi; = 175&deg;. Moreover, the particle flux is collimated in order that the tested plasma volume is small (the diameter is about 10 mm on magnetic axis). Due to the geometry of the device, the collected particle beam is very narrow and positioned almost perpendicular to magnetic field, therefore, the pitch of the collected particles is very small, tan<sup>-1</sup>(v<sub> ||</sub>/v<sub>per</sub>) &le; 3.1·10<sup>–2</sup> rad, which means that only the perpendicular velocity of trapped particles is measured.  
A radial profile is obtained using a series of reproducible discharges
<ref>R. Balbín et al, ''Ion confinement studies on the TJ-II stellarator '', [http://www-fusion.ciemat.es/SW2005/conferences/greifswald03/Balbin_053_SWS.pdf 14<sup>th</sup> Stellarator Workshop, Greifswald (2003)]</ref>
<ref>R. Balbín et al, ''Ion confinement studies on the TJ-II stellarator '', [http://www-fusion.ciemat.es/SW2005/conferences/greifswald03/Balbin_053_SWS.pdf 14<sup>th</sup> Stellarator Workshop, Greifswald (2003)]</ref>
<ref>J.M. Fontdecaba et al, ''Ion heat transport analysis in TJ-II plasmas'', [http://www-fusion.ciemat.es/SW2005/conferences/greifswald03/Fontdecaba_128_SWS.pdf 14<sup>th</sup> Stellarator Workshop, Greifswald (2003)]</ref>
<ref>J.M. Fontdecaba et al, ''Ion heat transport analysis in TJ-II plasmas'', [http://www-fusion.ciemat.es/SW2005/conferences/greifswald03/Fontdecaba_128_SWS.pdf 14<sup>th</sup> Stellarator Workshop, Greifswald (2003)]</ref>
<ref>J.M. Fontdecaba, F. Castejón, R. Balbín et al., ''Energy-Resolved Neutral Particle Fluxes in TJ-II ECRH Plasmas'', [http://www.new.ans.org/pubs/journals/fst/a_565 Fusion Sc. Technol. '''46''' (2004) 271]</ref>
<ref>J.M. Fontdecaba, F. Castejón, R. Balbín et al., ''Energy-Resolved Neutral Particle Fluxes in TJ-II ECRH Plasmas'', [http://www.new.ans.org/pubs/journals/fst/a_565 Fusion Sc. Technol. '''46''' (2004) 271]</ref>
<ref>J.M. Carmona, K.J. McCarthy, R. Balbín, and S. Petrov, ''Charge-exchange spectroscopic diagnostic for the TJ-II stellarator'', [[doi:10.1063/1.2229200|Rev. Sci. Instrum. '''77''' (2006) 10F107]]</ref>
<ref>J.M. Carmona, K.J. McCarthy, R. Balbín, and S. Petrov, ''Charge-exchange spectroscopic diagnostic for the TJ-II stellarator'', [[doi:10.1063/1.2229200|Rev. Sci. Instrum. '''77''' (2006) 10F107]]</ref>
and the obtained profiles have been modelled.
<ref>F. Castejón, J. M. Reynolds, J. M. Fontdecaba, R. Balbín, J. Guasp, D. López-Bruna, I. Campos, L. A. Fernández, D. Fernández-Fraile, V. Martín-Mayor and A. Tarancón, ''Ion Orbits and Ion Confinement Studies on ECRH Plasmas in TJ-II Stellarator'', [[doi:10.13182/FST06-A1263|Fusion Sci. Technol. '''50''', 3 (2006) 412]]</ref>
Impurity ion temperatures and poloidal velicties have also been obtained.
Impurity ion temperatures and poloidal velicties have also been obtained.
<ref>J.M. Carmona, K.J. McCarthy, V. Tribaldos, and M.A. Ochando, ''Temperature profiles using CXRS in the TJ-II stellarator'', [http://www.jspf.or.jp/PFR/PDF/pfr2008_03-S1044.pdf Plasma Fusion Res. '''3''' (2008) S1044]</ref>
<ref>J.M. Carmona, K.J. McCarthy, V. Tribaldos, and M.A. Ochando, ''Temperature profiles using CXRS in the TJ-II stellarator'', [http://www.jspf.or.jp/PFR/PDF/pfr2008_03-S1044.pdf Plasma Fusion Res. '''3''' (2008) S1044]</ref>


The diagnostic can be controlled remotely.
The diagnostic can be controlled remotely.