90° cylindrical analyzer for the plasma potential fluctuations measurements by heavy ion beam diagnostic on the tokamak ISTTOK

Nedzelskiy, I. S.; Malaquias, A.; Sharma, R.; Henriques, R.

doi:10.1016/j.fusengdes.2017.03.097

Cited by 6 publications

(16 citation statements)

References 11 publications

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“…This is typical for all traditional HIBDs operated with the injection of the angle-scanned primary beam ( Figure 1 b) and the mirror-type 30° Proca-Green electrostatic energy analyzer [ 3 ]. On ISTTOK, the HIBD is operated with the fixed injection angle of the primary beam ( Figure 1 a) and employs the 90° cylindrical energy analyzer (90° CEA) due to its multichannel operation ability along the analyzer non-dispersive direction [ 5 ]. Figure 7 shows the schematic of the 90° CEA arrangement on ISTTOK.…”

Section: Split-plate Detection and Spd Transfer Characteristicsmentioning

confidence: 99%

“…The plasma potential Φ pl in measurements with 90° CEA is obtained from relation [ 5 ]: ( Φ pl / E 0 ) = [( w b /2 R 0 )/ C E ] δi , where w b is the beam width, R 0 is the central radios of 90° CEA, C E is the energy dispersion coefficient and E 0 is the beam energy.…”

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

“…The number and minimal width of the cells of MCAD in Figure 16 can be estimated from the analyzer dynamic range, (Δ E / E 0 ) DR , and the minimum detectable change of ion beam energy, (Δ E / E 0 ) min , determined by the signal-to-noise ratio (SNR) of the beam current measured on the cell. As an example, for the 90° CEA, the (Δ E / E 0 ) DR and (Δ E / E 0 ) min in terms of δi are [ 5 ]: (Δ E / E 0 ) DR = [( w b / R 0 )/ C E ], ( δi = ±1) (Δ E / E 0 ) min = [( w b /2 R 0 )/ C E ](SNR) −1 , ( δi = (SNR) −1 ). …”

Section: Multiple-cell and Multi-split-plate Detectionmentioning

confidence: 99%

“…The curves plotted in that way represent the deviations induced by beam profile in the measurements of plasma potential as a function of the secondary beam centerline position h. Note up to 40% deviation on δi B in the case of the bell-shape beam profile (B), if the center of the secondary beam is positioned at h 0 = 0.4 inside the dynamic range window. The plasma potential Φpl in measurements with 90° CEA is obtained from relation [5]:…”

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

“…Figure 10 shows the δi response on harmonic variation of the secondary beam position on SPD, given by: h = h0 + ahsin(t), (8) for bell-shape (δiB, Figure 10a) and ideal uniform (δiI, Figure 10b) beams, ah = 0.1 and different h0. The plasma potential Φ pl in measurements with 90 • CEA is obtained from relation [5]:…”

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

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Affect of Secondary Beam Non-Uniformity on Plasma Potential Measurements by HIBD with Split-Plate Detector

Nedzelskiy

Malaquias

Henriques

et al. 2022

Sensors

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In a Heavy Ion Beam Diagnostic (HIBD), the plasma potential is obtained by measuring the energy of the secondary ions resulting from beam-plasma collisions by an electrostatic energy analyzer with split-plate detector (SPD), which relates the secondary ion beam energy variation to its position determined by the difference in currents between the split plates. Conventionally, the data from SPD are analyzed with the assumption that the secondary beam current is uniform. However, the secondary beam presents an effective projection of the primary beam, the current of which, as a rule, has a bell-like non-uniform profile. This paper presents: (i) the general features of the secondary beam profile formation, considered in the simplistic approximation of the circular primary beam and the secondary ions that emerge orthogonal to the primary beam axis, (ii) details of spit-plate detection and the influence of the secondary beam non-uniformity on plasma potential measurements, (iii) supported experimental data from the tokamak ISTTOK HIBD for primary and secondary beam profiles and the SPD transfer characteristic, obtained for the 90° cylindrical energy analyzer (90° CEA) and (iv) the implementation of a multiple cell array detector (MCAD) with dedicated resolution for the measurements of secondary beam profile and MCAD operation in multi-split-plate detection mode for direct measurements of the SPD transfer characteristic.

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Section: Split-plate Detection and Spd Transfer Characteristicsmentioning

confidence: 99%

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

Section: Multiple-cell and Multi-split-plate Detectionmentioning

confidence: 99%

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

Section: The Influence Of the Secondary Beam Non-uniformity On Plasma...mentioning

confidence: 99%

See 3 more Smart Citations

Affect of Secondary Beam Non-Uniformity on Plasma Potential Measurements by HIBD with Split-Plate Detector

Nedzelskiy

Malaquias

Henriques

et al. 2022

Sensors

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The Heavy Ion Beam Probe Diagnostic and Applications

Melnikov

2019

Springer Series in Plasma Science and Technology

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Design and optimization of the electrostatic input module for the ISTTOK Tokamak HIBD cylindrical energy analyzer

Sharma¹,

Nedzelskiy²,

Malaquias³

et al. 2017

J. Inst.

Self Cite

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The Heavy Ion Beam Diagnostic of the ISTTOK Tokamak is based on the injection of a single ionized primary beam (Xe+, Cs+) of energy 20–25 keV and on the collection of all doubly ionized ions emerging from the primary beam due to the impact ionization with the plasma electrons. In the present configuration three local plasma parameters can be retrieved: plasma density (ne), electron temperature (Te), and poloidal magnetic field (Bp). A new detection system is being design in order to determine the plasma potential (Vp) profile via the secondary ions energy measurements. To that end an improved 90̂ cylindrical electrostatic analyzer (CEA) has been designed and optimized to measure the energy of the secondary ions. This paper reports on the design optimization of the input stage of the new detection arrangement to guide and shape 4 secondary beams into the entrance of the CEA. It is composed of a set of four electrostatic cylindrical plates followed by four pairs of steering plates and a multiple aperture Einzel-like electrostatic lens, consisting of four planar vertical electrodes containing four passing slits. Individual secondary beams with dimension of 8 mm × 2.5 mm were obtained without overlapping between the four beams from different slits. By changing the incident beam energy from 20 keV to 20.2 keV (in order to simulate a local plasma potential value of +200 V), without adjusting bias voltage of the input system, results in a vertical beam shift of 1 mm which can be recovered by changing the voltage on the parallel plate arrangement by 40 V. The flexibility and tolerance of the optic system was tested successfully for the expected angular uncertainty of the beam by +/−0.5̂ at the input module entrance and with the expected energy spread of the beam corresponding to different plasma positions inside the tokamak.

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90° cylindrical analyzer for the plasma potential fluctuations measurements by heavy ion beam diagnostic on the tokamak ISTTOK

Cited by 6 publications

References 11 publications

Affect of Secondary Beam Non-Uniformity on Plasma Potential Measurements by HIBD with Split-Plate Detector

Affect of Secondary Beam Non-Uniformity on Plasma Potential Measurements by HIBD with Split-Plate Detector

The Heavy Ion Beam Probe Diagnostic and Applications

Design and optimization of the electrostatic input module for the ISTTOK Tokamak HIBD cylindrical energy analyzer

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