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Neutral particle analyzer diagnostics on the TCV tokamak
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Image of FIG. 1.
FIG. 1.

5-ch.NPA layout: (1) TCV vacuum chamber, (2) plasma, (3) NPA duct, (4) NPA, and (5) view line .

Image of FIG. 2.
FIG. 2.

Scheme of the five-channel energy analyzer: (1) vacuum gate, (2) atom flux emitted by plasma, (3) analyzer inlet slit, (4) calibration thermal ion source, (5) inlet and outlet slits of the stripping cell, (6) vacuum gauges, (7) analyzing condenser, (8) Faraday cage for neutrals, (9) channel condensers, (10) electron multipliers, (11) input slits of energy channels, (12) turbo molecular pumps, (13) ion trajectories, (14) stripping cell, (15) cleaning condenser, (16) fore vacuum pump, and (17) nitrogen injection in stripping cell.

Image of FIG. 3.
FIG. 3.

Scheme of CNPA: (1) stripping and acceleration systems, (2) stripping foil, (3) analyzing magnet, (4) Hall probe, (5) analyzing electrostatic condenser, (6) shielding mask at the entrance to the detectors, (7) detectors, atomic flux emitted by plasma, and secondary ions.

Image of FIG. 4.
FIG. 4.

CNPA layout on TCV: (1) compact NPA, (2) entrance diaphragm , (3) calibration source of alkali ions, (4) bellow, (5) electrical break, (6) inlet diaphragm unit of collimator, (7) bypass for pumping from the atmosphere pressure and letting to air, (8) turbomolecular pump, (9) CNPA-TCV valve, (10) CNPA rotation point (bellow), (11) full-range vacuum gauge, (12) CNPA horizontal platform, (13) vertical platform, (14) fixed support, (15) DNB duct, (16) TCV plasma axis, (17) TCV port, (18) TCV vacuum vessel, (19) CNPA view cone, and (20) DNB path line.

Image of FIG. 5.
FIG. 5.

Energy profiles (instrumental functions) for deuterium detector array (ch. 12–28) in setup: (●)—calibration and (––)—Gaussian fit from modeling.

Image of FIG. 6.
FIG. 6.

Instrumental function for 18th CNPA channel (deuterium in setup 1): (●)—calibration, (—)—model with , , and , and (FWHM)—.

Image of FIG. 7.
FIG. 7.

Energy resolutions of the CNPA channels for deuterium array (deuterium in setup 1): (●)— (scattering), ◇— (finite detector size), and ▿—FWHM.

Image of FIG. 8.
FIG. 8.

Energy resolutions of the CNPA channels: ▴—hydrogen detector array in setup, ●—deuterium detector array in setup, ▾—deuterium detector array in setup, ◇—helium detector array in setup, close markers—experimental calibration, and open markers—evaluated with code.

Image of FIG. 9.
FIG. 9.

Detection efficiencies: ▴—hydrogen detector array in setup, ●—deuterium detector array in setup, ▾—deuterium detector array in setup, and ◆—helium detector array in setup.

Image of FIG. 10.
FIG. 10.

The thermal source of alkali ions.

Image of FIG. 11.
FIG. 11.

Differential spectrum of pulse heights from CEM detectors of CNPA.

Image of FIG. 12.
FIG. 12.

Measurement of channel energy characteristics with calibration source: (a) ion beam energy scan at and (b) analyzing condenser voltage scan at .

Image of FIG. 13.
FIG. 13.

(Color) Energy distribution of particles detected in low energy (14th) CNPA channel for : , , , and (all in keV).

Image of FIG. 14.
FIG. 14.

(Color) Energy distribution of particles detected in low energy (18th) CNPA channel for : , , , and (all in keV).

Image of FIG. 15.
FIG. 15.

Correction of channel mean energy (A) and energy resolutions (B) for the deuterium array of the CNPA in setup.

Image of FIG. 16.
FIG. 16.

(Color) Ion temperature measurement in TCV discharge No. 27114 by 5-ch.NPA: (a) with fast voltage sweeping applied to high voltage divider , (b) countrates from NPA, (c) ion temperature with temporal resolution of for .

Image of FIG. 17.
FIG. 17.

(Color) Charge exchange spectrum in No. 27114 from 5-ch.NPA: for . Colors correspond to different channels.

Image of FIG. 18.
FIG. 18.

(Color) NPA measurements with modulated DNB injection: (a) beam current, (b) 5-ch.NPA counting traces, and CNPA counting traces for (c) hydrogen and (d) deuterium.

Image of FIG. 19.
FIG. 19.

(Color) 5-ch.NPA CX spectra with and without DNB.

Image of FIG. 20.
FIG. 20.

(Color) CNPA CX spectra for hydrogen and deuterium with and without DNB; black line—Poisson statistics limit.

Image of FIG. 21.
FIG. 21.

(Color) TCV plasma discharge with H puff: (a) plasma current and line integrated density , (b) rate of H and D gas injections, and CNPA counting rates for low energy deuterium (c) and hydrogen (d) channels.

Image of FIG. 22.
FIG. 22.

(Color) H and D CX spectra before H-gas puff (experiment and DOUBLE-TCV simulation with )

Image of FIG. 23.
FIG. 23.

(Color) CX spectra (a) and density ratio (b) of hydrogen population generated by H puff during and after gas injection .


Generic image for table
Table I.

Calibration of the NPA energy resolution.

Generic image for table
Table II.

Characteristics of CEM KBL detectors.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Neutral particle analyzer diagnostics on the TCV tokamak