Investigation of the Clustering Condition for Various Gasses Ejected from a Fast Solenoid Valve for Supersonic Cluster Beam Injection

We propose an optical method based on Rayleigh scattering for the direct measurement of cluster tracks produced by a high-pressure gas jet. The tracks of the argon and methane clusters are acquired by a high-speed camera. It is found that the cluster sizes of these tracks are within the range of 7E + 03~1E + 07 for argon and 2E + 06~4E + 08 for methane. Most argon tracks are continuous and their intensity changes gradually, while the majority of the methane tracks are separated into discrete fractions and their intensity alters periodically along the flight path, which may indicate the methane clusters are more unstable and easily to break up. Special methane clusters which may fly at an axial velocity of less than 2.5m/s are also found. This method is very sensitive to large gas cluster and has broad application prospects in cluster physics.

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“…The fitted coefficient is 5.78, which happens to be the mean value of the two coefficients of 3.8 and 7.6 in ref. 20 .…”

Section: Resultsmentioning

confidence: 99%

“…According to the results from Akiyoshi Murakami et al . 20 , the relation between N c and Г* for methane is described in formula (2).…”

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confidence: 99%

The optical measurement of large cluster tracks in a gas jet

Chen

Liu

Han

et al. 2016

Sci Rep

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“…While the k parameter in the formula for * should account for differences between gases, there may be more subtle effects to consider. For example, while equation ( 2) suggests that substantial cluster formation should occur for roomtemperature hydrogen at an arbitrarily high P o , measurable numbers of hydrogen clusters have only been observed for temperatures below 180 K [22,23]. For P o of 50-250 psi (0.35-1.75 MPa) at 295 K, equation (4) predicts cluster sizes from 210-9200 molecules.…”

Section: Discussion On Cluster Formation and The Expected Cluster Pop...mentioning

confidence: 99%

Molecular hydrogen density measurements of short-pulse, high-density fuelling from a molecular cluster injector

2011

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A molecular cluster injector (MCI) has been developed to provide short-pulse, high-density fuelling for the lithium tokamak experiment (LTX). Using an electron-beam fluorescence method, the molecular density profiles produced by the injector are measured with sub-cm spatial resolution. The system, which is cryogenically cooled to promote the formation of molecular clusters, demonstrates a significant increase in molecular density relative to room-temperature supersonic gas injectors. The transient characteristics of short pulses (3–5 ms) are measured with 250 µs temporal resolution, and the jet shock structure is found to evolve significantly on that time scale. Supplemental measurements with a pressure transducer validate the electron-beam measurements. The measured density profiles are consistent with supersonic flows suitable for producing substantial populations of molecular clusters. The measured densities and flow rates are appropriate for high-density fuelling of LTX plasmas. The MCI will be used to investigate the physics of molecular cluster fuelling of LTX plasmas.

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“…SSGP is being developed as a new fueling method for the LHD [7,8]. In SSGP, high-pressure gas is ejected through a fast solenoid valve equipped with a Laval nozzle.…”

Section: Supersonic Gas Puffingmentioning

confidence: 99%

Observation of Electron-Temperature Fluctuations Triggered by Supersonic Gas Puffing in the LHD

Murakami

Miyazawa

Yasui

et al. 2011

Plasma and Fusion Research

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Non-local transport and electron temperature fluctuations triggered by supersonic gas puffing (SSGP) in high-temperature helical plasmas in the Large Helical Device (LHD) are reported. After a short-pulse SSGP, the core electron temperature increased while the edge electron temperature decreased. SSGP triggered a longer core temperature increase than that triggered by a small impurity pellet injection. The temperature profile, which was relatively flat inside the half minor radius before SSGP, became parabolic after non-local transport was triggered. Fluctuations were excited in the electron temperature signals around the half minor radius. The frequency of these fluctuations increased from ∼ 400 Hz to ∼ 1 kHz within ∼ 0.1 s and the amplitude decreased correspondingly. The temperature fluctuations inside and outside of the half minor radius had opposite phases. Magnetic fluctuations resonating near the half minor radius were observed simultaneously with the electron temperature fluctuations.

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Investigation of the Clustering Condition for Various Gasses Ejected from a Fast Solenoid Valve for Supersonic Cluster Beam Injection

Cited by 7 publications

References 7 publications

The optical measurement of large cluster tracks in a gas jet

The optical measurement of large cluster tracks in a gas jet

Molecular hydrogen density measurements of short-pulse, high-density fuelling from a molecular cluster injector

Observation of Electron-Temperature Fluctuations Triggered by Supersonic Gas Puffing in the LHD

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