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SPIDER radio-frequency (RF) inductively coupled ion source is a full-size prototype of ITER Heating Neutral Beam Injector ion source,equipped with 100 keV accelerator system for the particles. It is in operation since June 2018 in the premises of Neutral Beam Test Facility located in Padova, Italy. The ion source includes a plasma source where plasma is generated and heated by8 RF drivers operating with Hydrogen/Deuterium at a gas pressure of ~ 0.3 Pa and maximum RF power of 100 kW per driver at 1 MHz frequency. There are 4RF circuits present in SPIDER, each comprises of a RF generator and a RF load. The RF load is defined bya transmission line:a capacitor-basedmatching network and two driver coils connected in series. To qualify the performance of the driver, an estimation of the power transfer efficiency (PTE) to the plasma is important. It is defined as the ratio between the power absorbed by the plasma and the total RF input power. The power absorbed by the plasma cannot be measured experimentally and is found to be dependent on several parameters coupled together. Previously, a methodology has been developed based on the integration of various input parameters, plasma heating mechanisms and an electrical model which can provide an estimation of PTE to the plasma. One of the essential input parameters is the plasma electron density.It is possible to experimentally measure this parameter and currently different methods are being explored,but usually they also require a detailed and time consuming data analyses. In this perspective, are liable and a fast model will be beneficial for the estimation of electron density. This work will focus on the description, application,and comparison of different ways to estimate the electron density.Based on the available literature, two main approaches are highlighted for the estimation of electron density1) from the power balance equation and 2) through the measurements of the electrical parameters in the RF power circuits.The results in terms of electron density will be compared to the first experimental results obtained from spectroscopic and/or electrostatic probe measurements.

10 págs.; 12 figs.; 1 tab., The spatial-temporal evolution of muscle tissue sample plasma induced by a high-power transversely excited atmospheric (TEA) CO2 pulsed laser at vacuum conditions (0.1–0.01 Pa) has been investigated using high-resolution optical emission spectroscopy (OES) and imaging methods. The induced plasma shows mainly electronically excited neutral Na, K, C, Mg, H, Ca, N and O atoms, ionized C+, C2 +, C3 +, Mg+, Mg2 +, N+, N2 +, Ca+, O+ and O2 + species and molecular band systems of CN(B2Σ+–X2Σ+), C2(d3Πg–a3Πu), CH(B2Σ−–X2Π; A2Δ–X2Π), NH(A3Π–X3Σ−), OH(A2Σ+–X2 Σ+), and CaOH(B2Σ+–X2Σ+; A2Π–X2Σ+). Time-resolved two-dimensional emission spectroscopy is used to study the expanded distribution of different species ejected during ablation. Spatial and temporal variations of different atoms and ionic excited species are reported. Plasma parameters such as electron density and temperature were measured from the spatio-temporal analysis of different species. Average velocities of some plasma species were estimated. © 2015 Elsevier B.V. All rights reserved., We gratefully acknowledge the support received in part by the DGICYT (Spain) Project MICINN: CTQ2013-43086-P for this research. The authors wish to thank the Geomaterials2 Program (S2013/MIT 2914) supported by the Comunidad de Madrid and EU structural and cohesion funds (FSE and FEDER).

航空宇宙技術研究所 6-7 JUN. 1996 東京 日本, National Aerospace Laboratory 6-7 JUN. 1996 Tokyo Japan, HYFLEXで極超音速飛行あるいは再突入飛行のもとでのブラックアウト現象を研究するために反射率計による測定を行った。電波の反射強度と位相を反射率計により測定した。飛行データ解析は2段階から構成される。第一は実在気体効果を含むCFD(数値流体力学)コードを用いて機体周りの電子数密度分布を計算し、第二はCFD結果を使って電波反射解析をおこなった。この電波反射解析を用いて、電波の反射強度と位相を求め、これらの結果を飛行データと比較した。HYFLEXでの反射率計測定の概略を示し、実在気体効果を含むCFDコードについても記述した。計算結果、特に飛行軌跡に沿った自由電子密度分布を紹介した。飛行軌跡上の幾つかの点で、反射強度を計算し飛行データと比較した。2温度モデル、1温度モデルなどの熱モデル、あるいは完全触媒壁、非触媒壁などの表面条件を変える計算結果の幾つかについても報告した。, In HYFLEX, reflectometer measurements were performed to research the blackout phenomena under hypersonic or reentry flight. Reflection intensity and phase of radio wave were measured by reflectometer. Flight data analysis is composed of two steps. First is to calculate a distribution of electron number density around the vehicle by using a CFD (Computational Fluid Dynamics) code including the real gas effects. Second is to make the radio wave reflection analysis with CFD results. By using this radio wave reflection analysis, reflection intensity and phase of radio wave can be gotten and these results are compared with the flight data. The outline of the reflectometer measurement in HYFLEX is shown in this paper. Also the CFD code, including the real gas effects is described. Calculation results, especially free electron density distributions along the flight trajectory are presented. In some points on the flight trajectory, reflection intensity was calculated and compared with the flight data. Some results of the calculations which change thermal model, two-temperature model and one-temperature model or surface condition, fully catalytic surface and noncatalytic surface, are also presented., 資料番号: AA0000685010, レポート番号: NAL SP-34

24-25 Jul. 1996, 極超音速での飛行中には機体まわりの気体が電解離してプラズマ状態になることが知られている。このため、プラズマ層によって電波が反射されブラックアウト現象が生じ、また、温度や圧力が気体の電解離を仮定しない場合の予測からはずれる。ところが、この種のデータは地上試験で得ることが困難であり、今回のHYFLEX(極超音速飛行実験)機飛行試験はこの種のデータを取得できる貴重な機会である。HYFLEXでは、機体まわりで生じる気体の電離現象を、リフレクトメータによって機上から測定した。取得したデータは、電波の反射強度および位相の変化である。一方、飛行試験結果と比較するため、実在気体CFD(数値流体力学)コードを用いた数値解析によってプラズマ密度場を計算し、この結果を用いて電波反射解析を行った。飛行試験結果と数値計算結果はよく一致し、実在気体CFDコードの結果を、プラズマ電子密度に換算して2倍程度の誤差で検証することができた。今後、電波反射解析手法の検討などにより、さらに検証精度を上げる必要があるが、本飛行試験データは、機体まわりのプラズマ電子密度場の基礎データとして、また、CFDおよび電波反射解析手法の検証データとして非常に有用であった。, It is known to become a plasma state by electrolyzing the gas around the vehicle under hypersonic speed flight. Therefore, the radio wave is reflected by the plasma layer, and the blackout phenomena occurs. In the other, it is also reported that temperature, pressure and density around the vehicle deviates from the prediction which do not assume electrolyzing of the gas. Although it is difficult to obtain the such kind of data in the ground test, present HYFLEX (Hypersonic Flight Experiment) plan is the precious opportunity which can acquire the data of plasma state around the vehicle. In HYFLEX, it was planned that the ionizing phenomena of the gas around the airframe was measured by the reflectometer from the onboard, and the data acquisition was done. Acquired data is the change of reflection intensity and phase of the radio wave. In the meantime, the plasma density field was calculated using the real gas CFD (Computational Fluid Dynamics) code and the radio wave reflection analysis was carried out in order to compare with the flight test. Flight test result and numerical calculation result agreed well, and the real gas CFD code was verified at an error of about two times by the conversion to the plasma electron density. Although the verification accuracy has to be raised more by examination of the radio wave reflection analysis technique, etc., this flight test data was very useful as basic data of plasma electron density field around hypersonic flight vehicle, and as verification data of real gas CFD code and the radio wave reflection analysis technique., 資料番号: AA0000584020, レポート番号: NAL SP-32

Emission spectroscopy and the recording of the electrical characteristics are used to study the influence of the granulometric composition of the arc-quenching material. Six adjacent intervals of grain size are studied: each of them is 50 µm wide, and the upper limit of the global interval is lower than 1000 µm. The final dimensions of the fulgurite are found to be proportional to the granulometry. Concerning the electrical parameters, two groups are pointed out : the extinction time constant, the dissipated energy and the value decrease with the granulometry, whereas the maximum value of the arc voltage increases with the granulometry. The rate of decrease of the temperature depends on the time interval observed: at the beginning of the arcing period, the decrease is fastest for the smallest granulometric parameters; and during the last part of the arcing period the trend is reversed. At the beginning of the arcing period, the electron number density increase varies between 10E19 and 10E20 cm-3.ms-1. When the electric current decreases, the electron number density decreases exponentially with a time constant value ranging from 0.40 ms to 0.25 ms.

This paper describes an experimental set up used to investigate the physcical parameters of the arc, in fact the temperature and the electron density. Improvements have been made from the last set up. Fuses studied here are High Breaking Capacity fuses (HBC). In this study, the arc dissipates 1 200 J, the peak of current is about 2 200 A and the duration of the arc is 3 ms. The whole of the visible spectrum has been registered, from 360 nm to 800 nm, in the exploding part of the arc. The spectrum consists of continuous light together with spectral lines appear mostly when the electric current decreases. The behaviour of the spectra show that there is a big gradient of species concentrations in the arc, together with a high gradient of temperature. The temperature is measured from Si II lines and metallic spectral transitions. The calculations show a decrease from about 17 000 K at the beginning of the phenomenon, until about 7 000 K at 4 ms after the beginning of the electric current. The measured values of the electron density vary between 10E17 cm-3 and 10E19 cm-3.