Measurement of number density and size distribution of dust in DIII-D during normal plasma operation

West, W.P.; Bray, B.D.; Burkart, Johannes

doi:10.1088/0741-3335/48/11/007

Cited by 45 publications

(48 citation statements)

References 17 publications

(33 reference statements)

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“…1c) due to dust ablation in TEXTOR plasmas. The evaluation of dust concentration immediately after dust mobilization provided a value of 0.5 particle/cm 3 which is about 100 times higher than that measured for intrinsic dust in DIII-D [19].…”

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confidence: 60%

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Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Litnovsky

Rudakov

Bozhenkov

et al. 2013

Journal of Nuclear Materials

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Dust will have severe impact on ITER performance since the accumulation of tritium in dust represents a safety issue, a possible reaction of dust with air and steam imposes an explosion 2 hazard and the penetration of dust in core plasmas may degrade plasma performance by increasing radiative losses. Investigations were performed in TEXTOR where known amounts of pre-characterized carbon, diamond and tungsten dust were mobilized into plasmas using special dust holders.Mobilization of dust changed a balance between plasma-surface interactions processes, significantly increasing net deposition. Immediately after launch dust was dominating both core and edge plasma parameters. Remarkably, in about 100 milliseconds after the launch, the effect of dust on edge and core plasma parameters was vanished: no increase of carbon and tungsten concentrations in the core plasmas was detected suggesting a prompt transport of dust to the nearby plasma-facing components without further residence in the plasma. PSI 2012

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confidence: 60%

“…An additional, smaller 6 intensity launch occurred during the start of NBI, due to further increase of the plasma load. The usual amount of mobilized impurities was about 5×10 19 atoms, the maximum amount did not exceed 1.6×10 21 atoms.…”

Section: Mobilization Of Dust In Textor Plasmamentioning

confidence: 86%

Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Litnovsky

Rudakov

Bozhenkov

et al. 2013

Journal of Nuclear Materials

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“…Dust particles in tokamaks were first detected by a standard TS diagnostics with the use of Mie scattering [11]. Possibilities of such diagnostic are restricted by (1) a very high intensity of laser probing beams which burns small particles out before they have been detected, (2) a short laser pulse duration and small probing volume which reduces the sensitivity and detection probability of dust particles Mie scattering at the laser probing wavelength causes the diagnostic to be affected by stray light.…”

Section: Pos(ecpd2015)034mentioning

confidence: 99%

Thomson Scattering With Multi-Pass Intra-Cavity Laser System For The Study Of Fast Changing Structures In Fusion Plasma

Kantor¹

2016

Proceedings of 1st EPS Conference on Plasma Diagnostics — PoS(ECPD2015)

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Advanced Thomson Scattering (TS) diagnostics with a Laser Intra-cavity Multi-pass Probing (LIMP) system were developed and implemented in several tokamaks in recent decades. The LIMP system provides a significant gain of the laser probing energy along with generation of many pulses at a high repetition rate within a single pumping pulse. Probing lasers with a LIMP system have considerably extended the capability of the TS diagnostic and have opened new application fields in plasma physics.The paper presents the principles of the LIMP system which underlie its efficiency as well as some of its applications in physical studies performed in the TEXTOR tokamak. The TS diagnostic with LIMP has enabled detailed measurements of fluctuations of electron temperature and density along the whole plasma diameter. The structure of these fluctuations, which are typically 1-2% in amplitude, has been resolved. The diagnostic made it possible to measure the fine structure of rotating magnetic islands in the TEXTOR plasma. The observed structures significantly differ from the classical shape of helical magnetic perturbations.LIMP is applied for measurements of not only electrons but also of other plasma particles. Laser-heated dust micro-particles were detected in plasma via their thermal radiation. The diagnostic provides the location of particles along with its velocity, temperature and dimension.

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“…The machine is outfitted with advanced plasma diagnostics including a Thomson scattering system based on 8 ND:YAG lasers and used primarily for the measurements of the electron density and temperature profiles. Spectrally nonshifted detector channels allow for detection of dust particles via Mie scattering [6,7]. The diagnostic can resolve the size of small particles between 50-250 nm in diameter.…”

Section: Measurements Of Naturally Occurring Dustmentioning

confidence: 99%

“…Nevertheless, statistical analysis of the data provides an estimate of the total dust content in the edge and scrape-off layer (SOL) plasmas and allows establishing trends in the dust production rates. It has been shown that during normal plasma operations in DIII-D dust is not a major impurity source, with total carbon content of the dust being less than a few percent of the plasma carbon impurity content [6]. Statistical evidence points to increased dust production in discharges with edge localized modes (ELMs) and disruptions.…”

Section: Measurements Of Naturally Occurring Dustmentioning

confidence: 99%

Dust Studies in DIII-D Tokamak

Rudakov¹,

West²,

Groth

et al. 2008

AIP Conference Proceedings

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Abstract. Studies of submicron dust using Mie scattering from Nd:YAG lasers and video data of micron to sub-millimeter sized dust on DIII-D tokamak have provided the first data of dust sources and transport during tokamak discharges. During normal operation on DIII-D dust observation rates are low, a few events per discharge or less. The net carbon content of the dust corresponds to a carbon atom density a few orders of magnitude below the core impurity density. Statistical analysis of Mie data collected over months of operation reveal correlation of increased dust rate with increased heating power and impulsive wall loading due to edge localized modes (ELMs) and disruptions. Generation of significant amounts of dust by disruptions is confirmed by the camera data. However, dust production by disruptions alone is insufficient to account for estimated in-vessel dust inventory in DIII-D. After an extended entry vent, thousands of dust particles are observed by cameras in the first 2-3 plasma discharges. Individual particles moving at velocities up to ~300 m/s, breakup of larger particles into pieces, and collisions of particles with walls are observed. After ~70 discharges, dust levels are reduced to a few events per discharge. In order to calibrate diagnostics and benchmark modeling, milligram amounts of micron-sized carbon dust have been injected into DIII-D discharges, leading to the core carbon density increase by a factor of 2-3. Following injection, dust trajectories in the divertor are mostly in the toroidal direction, consistent with the ion drag force. Dust from the injection is observed in the outboard midplane by a fast framing camera. The observed trajectories and velocities of the dust particles are in qualitative agreement with modeling by the 3D DustT code.

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Measurement of number density and size distribution of dust in DIII-D during normal plasma operation

Cited by 45 publications

References 17 publications

Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Dust investigations in TEXTOR: Impact of dust on plasma–wall interactions and on plasma performance

Thomson Scattering With Multi-Pass Intra-Cavity Laser System For The Study Of Fast Changing Structures In Fusion Plasma

Dust Studies in DIII-D Tokamak

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