Effects of operating parameters on the beam species of DIII-D neutral beam ion sources

Rao, Hong; Chiu, H.K.

doi:10.1109/fusion.2002.1027637

Cited by 7 publications

(4 citation statements)

References 1 publication

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“…The purpose of these channels is to measure and isolate any fluctuation components on the neutral beam itself that do not represent local plasma fluctuations and thus should be subtracted from the measured signals [14]. Such common-mode fluctuations arise predominantly from fluctuations in the neutral beam ion source [19], as well as large-amplitude edge fluctuations that become imprinted on the beam due to fluctuating beam attenuation. Such fluctuations are superimposed on the measured local fluctuations and can thus complicate analysis.…”

Section: Overview Of the Beam Emission Spectroscopy Diagnosticmentioning

confidence: 99%

Plasma Turbulence Imaging via Beam Emission Spectroscopy in the Core of the DIII-D Tokamak

McKee

Fonck

Gupta

et al. 2007

Plasma and Fusion Research

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Beam Emission Spectroscopy (BES), a high-sensitivity, good spatial resolution imaging diagnostic system, has been deployed and recently upgraded and expanded at the DIII-D tokamak to better understand density fluctuations arising from plasma turbulence. The currently deployed system images density fluctuations over an approximately 5 × 7 cm region at the plasma mid-plane (radially scannable over 0.2 < r/a ≤ 1) with a 5 × 6 (radial × poloidal) grid of rectangular detection channels, with one microsecond time resolution. BES observes collisionally-induced, Doppler-shifted D α fluorescence (λ = 652-655 nm) of injected deuterium neutral beam atoms. The diagnostic wavenumber sensitivity is approximately k ⊥ < 2.5 cm −1 , allowing measurement of longwavelength (k ⊥ ρ I < 1) density fluctuations. The recent upgrade includes expanded fiber optics bundles, customdesigned high-transmission, sharp-edge interference filters, ultra fast collection optics, and enlarged photodiode detectors that together provide nearly an order of magnitude increase in sensitivity relative to an earlier generation BES system. The high sensitivity allows visualization of turbulence at normalized density fluctuation amplitudes ofn/n < 1%, typical of fluctuation levels in the core region. The imaging array allows for sampling over 2-3 turbulent eddy scale lengths, which captures the essential dynamics of eddy evolution, interaction and shearing.

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Section: Overview Of the Beam Emission Spectroscopy Diagnosticmentioning

confidence: 99%

Plasma Turbulence Imaging via Beam Emission Spectroscopy in the Core of the DIII-D Tokamak

McKee

Fonck

Gupta

et al. 2007

Plasma and Fusion Research

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“…General "rules of thumb" exist for ion source tuning to affect the atomic/molecular species mix. 38 It may be possible to vary and control the source parameters stably to provide significant beam component variation on the fly, thereby altering the deposition profile in a controlled fashion. This can serve as an additional experimental knob for advanced profile control, e.g., varying the off axis beam current drive without altering the beam trajectory.…”

Section: Discussionmentioning

confidence: 99%

Determination of neutral beam energy fractions from collisional radiative measurements on DIII-D

Thomas

Grierson

Burgos

et al. 2012

Review of Scientific Instruments

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Neutral beams based on positive ion source technology are a key component of contemporary fusion research. An accurate assessment of the injected beam species mix is important for determining the actual plasma heating and momentum input as well as proper interpretation of beam-based diagnostics. On DIII-D, the main ion charge-exchange spectroscopy system is used to extract well-resolved intensity ratios of the Doppler-shifted D(α) emission from the full, half, and third energy beam components for a variety of beam operational parameters. In conjunction with accurate collisional-radiative modeling, these measurements indicate the assumed species mix and power fractions can vary significantly and should be regularly monitored and updated for the most accurate interpretation of plasma performance. In addition, if stable active control of the power fractions can be achieved through appropriate source tuning, the resulting control over the deposition profile can serve as an additional experimental knob for advanced tokamak studies, e.g., varying the off axis beam current drive without altering the beam trajectory.

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“…The first LPIS (LPIS-1) is composed of a plasma generator and a set of prototype tetrode accelerators. The plasma generator and beam accelerator, called a US common long pulse ion source (US CLPIS), were originally developed by General Atomics (GA) in USA [13,14]. The LPIS-1 consists of a magnetic bucket plasma generator with multi-pole cusp fields, and a set of tetrode accelerators with molybdenum slit apertures.…”

Section: Introductionmentioning

confidence: 99%

Estimation of Ion Beam Trajectories for a Slot Aperture Accelerator of Long-Pulse Ion Source in Neutral Beam Injector

Chang

2013

OJAppS

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A neutral beam injection (NBI) system has been developed and is being tested for an Experimental Advanced Superconducting Tokamak (EAST) device. The NBI system needs to be employed for an auxiliary heating and current drive of EAST plasmas. The first long pulse ion source (LPIS-1) has been installed in the neutral beam test bed (NBTB) system, and the performance is being tested in the NBTB. The LPIS-1 consists of a magnetic bucket plasma generator with multipole cusp-fields and a set of tetrode accelerators with slit-type apertures (a transparency of 60%). The ion beam trajectories of the accelerator column are estimated for the LPIS-1, including an original structure, with the change of slit aperture distance, plasma grid shape, grid gap distance, and voltage ratio between a plasma grid and a gradient grid using the IGUN code. This kind of calculation for the ion beam trajectory may be useful for the estimation of beam extraction characteristics and the direction of accelerator upgrade or modification, prior to the experiments of ion beam extraction.

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Effects of operating parameters on the beam species of DIII-D neutral beam ion sources

Cited by 7 publications

References 1 publication

Plasma Turbulence Imaging via Beam Emission Spectroscopy in the Core of the DIII-D Tokamak

Plasma Turbulence Imaging via Beam Emission Spectroscopy in the Core of the DIII-D Tokamak

Determination of neutral beam energy fractions from collisional radiative measurements on DIII-D

Estimation of Ion Beam Trajectories for a Slot Aperture Accelerator of Long-Pulse Ion Source in Neutral Beam Injector

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