Name: applying x-ray imaging crystal spectroscopy for use as a high temperature plasma diagnostic
Uploaded: 2016-08-25T13:00:00.000+00:00
Duration: 6 min 46 s
Description: Watch this Scientific Journal Video about Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic at JoVE.com

The authors would like to thank Matt Reinke and the Alcator C-Mod team for designing, building, and testing HIREXSR. This work was supported by DOE Contract Nos. DE-FC02-99ER54512 and DE-AC02-76CH03073.

<ol>
	<li>Reinke, M. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=X-ray+imaging+crystal+spectroscopy+for+use+in+plasma+transport+research.">X-ray imaging crystal spectroscopy for use in plasma transport research.</a> Rev. Sci. Instrum. 83 (11), 113504 (2012).</li><li>Hill, K. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+High+Resolution+X-Ray+Imaging+Crystal+Spectrometer+for+Measurement+of+Ion-Temperature+and+Rotation-Velocity+Profiles+in+Fusion+Energy+Research+Plasmas.">Development of a High Resolution X-Ray Imaging Crystal Spectrometer for Measurement of Ion-Temperature and Rotation-Velocity Profiles in Fusion Energy Research Plasmas.</a> Plasma Fusion Res. 2, 1067-1067 (2007).</li><li>Greenwald, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=20+years+of+research+on+the+Alcator+C-Mod+tokamak.">20 years of research on the Alcator C-Mod tokamak.</a> Phys. Plasmas. 21 (11), 110501 (2014).</li><li>Rice, J. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=X-ray+observations+of+medium+Z+H-+and+He-like+ions+with+satellites+from+C-Mod+tokamak+plasmas.">X-ray observations of medium Z H- and He-like ions with satellites from C-Mod tokamak plasmas.</a> J. Phys. B. 48 (14), 144013 (2015).</li><li>Ince-Cushman, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rotation+studies+in+fusion+plasmas+via+imaging+X-ray+crystal+spectroscopy.">Rotation studies in fusion plasmas via imaging X-ray crystal spectroscopy.</a> Rev. Sci. Instrum. 79, (2008).</li><li>Zachariasen, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Theory of X-Ray Diffraction in Crystals. , (2004).</li><li>Johann, H. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Die+Erzeugung+lichtstarker+R&#246;ntgenspektren+mit+Hilfe+von+Konkavkristallen.">Die Erzeugung lichtstarker R&#246;ntgenspektren mit Hilfe von Konkavkristallen.</a> Zeitschrift f&#252;r Physik. 69 (3-4), 185-206 (1931).</li><li>Wang, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Calculation+of+the+Johann+error+for+spherically+bent+x-ray+imaging+crystal+spectrometers.">Calculation of the Johann error for spherically bent x-ray imaging crystal spectrometers.</a> Rev. Sci. Instrum. 81 (10), (2010).</li><li>Eikenberry, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PILATUS:+a+two-dimensional+X-ray+detector+for+macromolecular+crystallography.">PILATUS: a two-dimensional X-ray detector for macromolecular crystallography.</a> Nucl. Instr. Meth. Phys. Res. A. 501 (1), 260-266 (2003).</li><li>Howard, N. T., Greenwald, M., Rice, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+impurity+confinement+on+Alcator+C-Mod+using+a+multi-pulse+laser+blow-off+system.">Characterization of impurity confinement on Alcator C-Mod using a multi-pulse laser blow-off system.</a> Rev. Sci. Instrum. 82 (3), 1-6 (2011).</li><li>Rice, J. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-local+heat+transport,+rotation+reversals+and+up/down+impurity+density+asymmetries+in+Alcator+C-Mod+ohmic+L-mode+plasmas.">Non-local heat transport, rotation reversals and up/down impurity density asymmetries in Alcator C-Mod ohmic L-mode plasmas.</a> Nucl. Fusion. 53, 033004 (2013).</li><li>Reinke, M. L., Podpaly, Y., Gao, C., Science, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Operation and Validation of The HIREXSR Analysis COde MIT-Plasma Science and Fusion Center Alcator C-Mod. , (2013).</li><li>Rosen, A. S., Reinke, M. L., Rice, J. E., Hubbard, A. E., Hughes, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Validation+of+x-ray+line+ratios+for+electron+temperature+determination+in+tokamak+plasmas.">Validation of x-ray line ratios for electron temperature determination in tokamak plasmas.</a> J. Phys. B. 47 (10), 105701 (2014).</li><li>Delgado-Aparicio, L. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-situ+wavelength+calibration+and+temperature+control+for+the+C-Mod+high-resolution+X-ray+crystal+imaging+spectrometer.">In-situ wavelength calibration and temperature control for the C-Mod high-resolution X-ray crystal imaging spectrometer.</a> Bull. Am. Phys. Soc. 55, (2010).</li></ol>

The authors have nothing to disclose.

I dati generati da questa tecnica possono essere utilizzati in un&#39;ampia varietà di studi sperimentali. temperatura Ion e profili di velocità toroidali possono essere utilizzati in una vasta gamma di studi di trasporto, compresa intrinseca rotazione del plasma auto-generato ed effetti perturbativi non locali. Misurare spettri di impurità iniettato attraverso laser blow-off può anche fornire informazioni importanti sul trasporto di impurità nel plasma, come è stato fatto a Howard et al. 2011 10.</s...

spettri X fornisce una ricchezza di informazioni su plasmi ad alta temperatura; per esempio, temperatura elettronica e la densità può essere dedotta da rapporti di intensità di linea. Usando uno spettrometro Johann visualizzazione plasma fuori asse, è possibile costruire profili di parametri del plasma quali densità, temperatura e velocità all&#39;interno del plasma con buona risoluzione spaziale 1,2 ore. Questo manoscritto presenta il funzionamento della High Resolution raggi X di cristallo Imaging Spectrometer con Risoluzione spaziale (HIREXSR), una risoluzione elevata lunghezza d&#39;onda spazialmente Imaging Spectrometer a raggi X utilizzato per visualizzare gli ioni idrogeno e di elio-like di elementi medio numero atomico in un tokamak plasma. HIREXSR viene distribuito su Alcator C-Mod, un dispositivo a fusione Tokamak con un raggio maggiore e minore di 0,67 m e 0,22 m, rispettivamente. E &#39;tipicamente opera con plasma di deuterio durata di ~ 2 sec con densità medie tra 0,2-8,0 x 10 20 m -3 </sup&gt; ed elettroni centrale temperature comprese tra 1-9 keV 3. In queste condizioni, medio elementi impurezze alto Z diventano altamente ionizzato e irradiare nella gamma dei raggi X, che HIREXSR misure. Benchmarking codice modellazione atomica degli spettri a raggi X ottenuto da plasmi di laboratorio ben diagnosticate-è importante per giustificare l&#39;uso di tali spettri per determinare i parametri del plasma quando le altre diagnostiche indipendenti non sono disponibili 4. Ogni spettrometro è costruito per il suo utilizzo desiderato. Di conseguenza, una descrizione generale sulla macchina ei suoi concetti correlati è necessario comprendere appieno questi potenti strumenti 5. Bragg riflessione si verifica quando un fotone riflessa strati adiacenti di un cristallo e percorre la distanza che è un multiplo della sua lunghezza d&#39;onda. Figura 1 illustra questo fenomeno. Questa condizione è espressa dall&#39;equazione nλ = 2 d sin θ b, dove n è l&#39;ordine del reflection, λ è la lunghezza d&#39;onda del fotone, d è la separazione tra strati adiacenti del cristallo e θ b è l&#39;angolo di Bragg. Una corrispondenza uno a uno tra λ e θ b indica che tutti i fotoni in un punto specifico del viaggio aereo rivelatore con la stessa lunghezza d&#39;onda. In pratica, tuttavia, di assorbimento e di precisione limitazioni manifestano come una deviazione dall&#39;angolo di Bragg. Ciò comporta solo una piccola gamma di angoli che producono significativa interferenza costruttiva, rappresentata da una curva dondolo 6. La figura 2 è una curva di esempio per un cristallo di calcite. HIREXSR è uno spettrometro Johann con un cristallo sferica piegato 7. Prima di descrivere questo tipo di dispositivo, una discussione di uno spettrometro semplice, circolare è appropriato. Questo set up è costituito da un cristallo curvato che riflette fotoni al rispettivo Bragg angoli perWards una serie di rilevatori di conteggio di fotoni singoli pixel a raggi X. Il cristallo ed il rivelatore depongono tangente alla circonferenza Rowland, come mostrato in figura 3. Il diametro del cerchio Rowland è uguale al raggio di curvatura del cristallo. Tutti i raggi provenienti da un determinato punto della circonferenza in qualsiasi punto sul cristallo hanno lo stesso angolo di incidenza rispetto al cristallo stesso. . Nel caso di HIREXSR, un permessi cristallo risoluzione spaziale sferica piegato in piano meridiano, illustrata nella figura 4 meridionale fuoco f m è definito come: f m = R c sin θ b, dove R c è il raggio di curvatura il cristallo. Il sagittale fuoco F s è definita come: F s = - f m / cos 2 θ b. La risoluzione spaziale dello spettrometro Δ x è datadi: <img alt="Equazione" src="/files/ftp_upload/54408/54408eq_DELTA_x.jpg" /> , Dove L cp è la distanza tra il cristallo e il plasma, e d è l&#39;altezza del cristallo. Poiché la spaziatura 2-dimensionale degli strati di cristallo è discreto, questo deve essere preso in considerazione quando si sceglie un materiale. Poiché le superfici del rivelatore sono piane, possono essere solo tangente al cerchio Rowland ad un certo punto, che dà quindi luogo ad errori dal raggi rilevati non sono atterraggio precisamente sui loro punti corrispondenti sul cerchio Rowland. Fisicamente, questo disallineamento manifesta come una &quot;spalmatura&quot; di fotoni di energia specifica sul rivelatore. Questo errore Johann è definito come <img alt="Equazione" src="/files/ftp_upload/54408/54408eq_delta_xj.jpg" /> , Dove L è la larghezza del cristallo. Se il rivelatore a pixel larghezza Ax p è molto più grande l&#39;errore Johann, allora la risoluzione spettrale è indipendente da esso. Se unre di dimensioni comparabili, quindi l&#39;errore totale può essere approssimata da <img alt="Equazione" src="/files/ftp_upload/54408/54408eq_delta_x_2.jpg" /> . Il potere risolutivo dello spettrometro cristallo è data da: <img alt="Equazione" src="/files/ftp_upload/54408/54408eq_lambda0.jpg" /> , dove <img alt="Equazione" src="/files/ftp_upload/54408/54408eq_delta_theta.jpg" /> . Invece di posizionare la tangente rivelatore ad un punto sul cerchio Rowland tuttavia, in HIREXSR rivelatore sia leggermente inclinato sacrificare accuratezza per la gamma spettrale, come mostrato in Figura 5. Questa analisi errore è stato sperimentalmente verificato e conforme alle aspettative 8. Ci sono due parametri fondamentali da considerare nella progettazione di uno spettrometro di Johann. In primo luogo, la gamma di imaging determina lo spettrometro verrà osservando. Per studiare plasmi, è altamente desiderabile per visualizzare tutta la sua sezione trasversale per distinguere tra spostamenti linea causati da poloidale e toroila rotazione dal. HIREXSR è montato in modo da poter visualizzare tutto il plasma, ed è inclinato leggermente fuori asse ~8 ° (illustrata nella figura 6) per consentire misurazioni accurate toroidali. In secondo luogo, risoluzione temporale regola il tempo minimo tra gli eventi che lo spettrometro può registrare. Per Alcator C-Mod, valori desiderabili sono inferiori a 20 msec, più brevi rispetto ai tempi di energia e di confinamento delle particelle. I rivelatori di conteggio dei pixel di raggi X che HIREXSR usi grado di supportare una risoluzione temporale di 6 a 20 msec o superiore 9. La tabella 1 riassume tutte le specifiche del modulo. Per gli studi di plasma perturbativi, il sistema blow-off laser su Alcator C-Mod vengono usati per fornire più ablazioni con tempi precisi 10. Il laser è un Nd: YAG (neodimio-drogato ittrio granato alluminio) operante a fino a 10 Hz. Il laser è incidente su un treno ottico telecomandato come mostrato nella figura 7 che si concentra e manziil fascio nella posizione desiderata sulla diapositiva. dimensioni spot del laser devono essere controllati in modo l&#39;iniezione non interrompe il plasma. Una lente convergente distanza focale (1.146 mm) viene traslato lungo l&#39;asse ottico tramite una fase lineare controllato a distanza per consentire formati di punto sottoposti ad intervento chirurgico per variano da ~0.5 a 7 mm. orientamento del fascio veloce è ottenuta tramite uno specchio piezoelettrico 2D. Questo sistema piezoelettrico è montato uno specchio RS232 guidato montaggio capace. Oltre al Nd: YAG, un diodo laser 633 nm viene utilizzata per indicare la posizione del fascio principale (infrarossi). Le travi sono fatte per essere collineari attraverso il primo specchio.

<table><tbody><tr><td>PILATUS 100k Detector System</td><td>DECTRIS</td><td>100k</td><td>Superseded by newer PILATUS3 detectors</td></tr><tr><td>Bragg Crystals</td><td>Kurchaov Institute</td><td>Custom Part</td><td></td></tr><tr><td>CaF&lt;sub&gt;2&lt;/sub&gt; Slides</td><td>LeBow</td><td>Custom Part</td><td></td></tr><tr><td>High Purity Argon</td><td>Airgas</td><td>AR HP300</td><td>Any high purity argon should work</td></tr><tr><td>Be window</td><td>Brush Wellman Electrofusion Products / Motion Hightech</td><td>Custom part</td><td></td></tr></tbody></table>

applying x-ray imaging crystal spectroscopy for use as a high temperature plasma diagnostic

spettri X fornisce una ricchezza di informazioni su plasmi ad alta temperatura; per esempio, temperatura elettronica e la densità può essere dedotta da rapporti di intensità di linea. Usando uno spettrometro Johann visualizzazione del plasma, è possibile costruire profili di parametri del plasma, quali la densità, la temperatura e la velocità con buona risoluzione spaziale e temporale. Tuttavia, l&#39;analisi comparativa codice modellazione atomica degli spettri a raggi X ottenuto da plasmi di laboratorio ben diagnosticate-è importante per giustificare l&#39;uso di tali spettri per determinare i parametri del plasma quando le altre diagnostiche indipendenti non sono disponibili. Questo manoscritto presenta il funzionamento della High Resolution raggi X di cristallo Imaging Spectrometer con Risoluzione spaziale (HIREXSR), una risoluzione elevata lunghezza d&#39;onda spazialmente Imaging Spectrometer a raggi X utilizzato per visualizzare gli ioni idrogeno e di elio-like di elementi medio numero atomico in un tokamak plasma. Inoltre, questo manoscritto riguarda un sistema blow-off laser che può introdurre tali ionial plasma con tempi precisi per consentire studi perturbativi di trasporto nel plasma.

Un campione di dati rappresentativi dal rivelatore a pixel per un bin tempo per lo spettro argon He-come è mostrato in Figura 17. Le linee spettrali, piegate in una forma ellittica dal cristallo sferica, sono chiaramente visibili. Il rivelatore superiore ha un pannello rilevatore di rotta, e ci sono alcuni pixel morti sparsi per tutti i rivelatori. I dati del pannello rilevatore di rotta dovrebbe essere ignorato. Fette dal rivelatore che mostra spettri misurati e risult...

Watch this Scientific Journal Video about Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic at JoVE.com

Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

spettri a raggi X offrono una ricchezza di informazioni sui plasmi ad alta temperatura. Questo manoscritto presenta il funzionamento di una risoluzione elevata lunghezza d&#39;onda spazialmente l&#39;imaging spettrometro a raggi X utilizzato per visualizzare ioni a idrogeno ed elio-come elementi di numero atomico medio in un plasma tokamak.

L&#39;applicazione di X-ray Imaging cristallo Spettroscopia per l&#39;uso come ad alta temperatura del plasma di diagnostica

X-ray spectra provide a wealth of information on high temperature plasmas; for example electron temperature and density can be inferred from line ...

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11.3K Views.  Massachusetts Institute of Technology.  spettri a raggi X offrono una ricchezza di informazioni sui plasmi ad alta temperatura. Questo manoscritto presenta il funzionamento di una risoluzione elevata lunghezza d'onda spazialmente l'imaging spettrometro a raggi X utilizzato per visualizzare ioni a idrogeno ed elio-come elementi di numero atomico medio in un plasma tokamak. 

Video: Applying X-ray Imaging Crystal Spectroscopy for Use as a High Temperature Plasma Diagnostic

Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a significant role in laser-material interaction, especially in the air environment1-11.
Early plasma evolution has been captured through pump-probe shadowgraphy1-3 and interferometry1,4-7. However, the studied time frames and applied laser parameter ranges are limited. For example, direct examinations of plasma front locations and electron number densities within a delay time of 100 picosecond (ps) with respect to the laser pulse peak are still very few, especially for the ultrashort pulse of a duration around 100 femtosecond (fs) and a low power density around 1014 W/cm2. Early plasma generated under these conditions has only been captured recently with high temporal and spatial resolutions12. The detailed setup strategy and procedures of this high precision measurement will be illustrated in this paper. The rationale of the measurement is optical pump-probe shadowgraphy: one ultrashort laser pulse is split to a pump pulse and a probe pulse, while the delay time between them can be adjusted by changing their beam path lengths. The pump pulse ablates the target and generates the early plasma, and the probe pulse propagates through the plasma region and detects the non-uniformity of electron number density. In addition, animations are generated using the calculated results from the simulation model of Ref. 12 to illustrate the plasma formation and evolution with a very high resolution (0.04 ~ 1 ps).
Both the experimental method and the simulation method can be applied to a broad range of time frames and laser parameters. These methods can be used to examine the early plasma generated not only from metals, but also from semiconductors and insulators.

An experimental method to examine the early plasma evolution induced by ultrashort laser pulses is described. Using this method, high quality images of early plasma are obtained with high temporal and spatial resolutions. A novel integrated atomistic model is used to simulate and explain the mechanisms of early plasma.

Indagine su Evolution Plasma precoce indotta da impulsi laser ultracorti

Early plasma is generated owing to high intensity laser irradiation of target and the subsequent target material ionization. Its dynamics plays a ...

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Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

Angolo-spettroscopia di fotoemissione risolta A ultra-basse temperature

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

Synthesis and Microdiffraction at Extreme Pressures and Temperatures

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 1 will be shown.

The laser heated diamond anvil cell combined with synchrotron micro-diffraction techniques allows researchers to explore the nature and properties of new phases of matter at extreme pressure and temperature (PT) conditions. Heterogeneous samples can be characterized in situ under high pressure by 2D mapping and combined powder, single-crystal and multigrain diffraction approaches.

Sintesi e microdiffrazione a pressioni e temperature estreme

High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary ...

How to Ignite an Atmospheric Pressure Microwave Plasma Torch without Any Additional Igniters

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a stable and continuous operation of the plasma is possible and the plasma torch can be used for many different applications. On one hand, the hot (3,600 K gas temperature) plasma can be used for chemical processes and on the other hand the cold afterglow (temperatures down to almost RT) can be applied for surface processes. For example chemical syntheses are interesting volume processes. Here the microwave plasma torch can be used for the decomposition of waste gases which are harmful and contribute to the global warming but are needed as etching gases in growing industry sectors like the semiconductor branch. Another application is the dissociation of CO2. Surplus electrical energy from renewable energy sources can be used to dissociate CO2 to CO and O2. The CO can be further processed to gaseous or liquid higher hydrocarbons thereby providing chemical storage of the energy, synthetic fuels or platform chemicals for the chemical industry. Applications of the afterglow of the plasma torch are the treatment of surfaces to increase the adhesion of lacquer, glue or paint, and the sterilization or decontamination of different kind of surfaces. The movie will explain how to ignite the plasma solely by microwave power without any additional igniters, e.g., electric sparks. The microwave plasma torch is based on a combination of two resonators &#8212; a coaxial one which provides the ignition of the plasma and a cylindrical one which guarantees a continuous and stable operation of the plasma after ignition. The plasma can be operated in a long microwave transparent tube for volume processes or shaped by orifices for surface treatment purposes.

This movie shows how an atmospheric plasma torch can be ignited by microwaves with no additional igniters and provides a stable and continuous plasma operation suitable for plenty of applications.

Come Ignite una Pressione atmosferica Microonde torcia al plasma senza alcuna accenditori supplementari

This movie shows how an atmospheric pressure plasma torch can be ignited by microwave power with no additional igniters. After ignition of the plasma, a ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

Emissione spettroscopica Boundary Investigation strato durante ablativo Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

High-resolution Thermal Micro-imaging Using Europium Chelate Luminescent Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient optical micro-imaging technique which can be used to map and quantify such behavior. Europium thenoyltrifluoroacetonate (EuTFC) has a 612 nm luminescence line whose activation efficiency drops strongly with increasing temperature, due to T-dependent interactions between the Eu3+ ion and the organic chelating compound. This material may be readily coated on to a sample surface by thermal sublimation in vacuum. When the coating is excited with ultraviolet light (337 nm) an optical micro-image of the 612 nm luminescent response can be converted directly into a map of the sample surface temperature. This technique offers spatial resolution limited only by the microscope optics (about 1 micron) and time resolution limited by the speed of the camera employed. It offers the additional advantages of only requiring comparatively simple and non-specialized equipment, and giving a quantitative probe of sample temperature.

Europium thenoyltrifluoroacetonate (EuTFC) has an optical luminescence line at 612 nm, whose activation efficiency decreases strongly with temperature. If a sample coated with a thin film of this material is micro-imaged, the 612 nm luminescent response intensity may be converted into a direct map of sample surface temperature.

Ad alta risoluzione termica micro-imaging Utilizzando europio chelato luminescenti Coatings

Micro-electronic devices often undergo significant self-heating when biased to their typical operating conditions. This paper describes a convenient ...

High Pressure Single Crystal Diffraction at PX^2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the GSECARS 13-BM-C beamline at the Advanced Photon Source. The DAC program at 13-BM-C is part of the Partnership for Extreme Xtallography (PX^2) project. BX-90 type DACs with conical-type diamond anvils and backing plates are recommended for these experiments. The sample chamber should be loaded with noble gas to maintain a hydrostatic pressure environment. The sample is aligned to the rotation center of the diffraction goniometer. The MARCCD area detector is calibrated with a powder diffraction pattern from LaB6. The sample diffraction peaks are analyzed with the ATREX software program, and are then indexed with the RSV software program. RSV is used to refine the UB matrix of the single crystal, and with this information and the peak prediction function, more diffraction peaks can be located. Representative single crystal diffraction data from an omphacite (Ca0.51Na0.48)(Mg0.44Al0.44Fe2+0.14Fe3+0.02)Si2O6 sample were collected. Analysis of the data gave a monoclinic lattice with P2/n space group at 0.35 GPa, and the lattice parameters were found to be: a = 9.496 &#177;0.006 &#197;, b = 8.761 &#177;0.004 &#197;, c = 5.248 &#177;0.001 &#197;, &#946; = 105.06 &#177;0.03&#186;, &#945; = &#947; = 90&#186;.

In this report, we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell at the GSECARS 13-BM-C beamline at the Advanced Photon Source. ATREX and RSV programs are used to analyze the data.

Alta pressione singolo cristallo di diffrazione a PX ^ 2

In this report we describe detailed procedures for carrying out single crystal X-ray diffraction experiments with a diamond anvil cell (DAC) at the ...

Chimica

Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose of efficiently driving non-equilibrium chemistry is discussed. The advantage of a flowing plasma reactor is that continuous chemical processes can be driven with the flexibility of startup times in the seconds timescale. The plasma approach is generically suitable for conversion/activation of stable molecules such as CO2, N2 and CH4. Here the reduction of CO2 to CO is used as a model system: the complementary diagnostics illustrate how a baseline thermodynamic equilibrium conversion can be exceeded by the intrinsic non-equilibrium from high vibrational excitation. Laser (Rayleigh) scattering is used to measure the reactor temperature and Fourier Transform Infrared Spectroscopy (FTIR) to characterize in situ internal (vibrational) excitation as well as the effluent composition to monitor conversion and selectivity.

This article describes a flowing microwave reactor that is used to drive efficient non-equilibrium chemistry for the application of conversion/activation of stable molecules such as CO2, N2 and CH4. The goal of the procedure described here is to measure the in situ gas temperature and gas conversion.

Plasma microonde non equilibrato per una chimica ad alta temperatura efficiente

A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose ...

An Atmospheric Pressure Plasma Setup to Investigate the Reactive Species Formation

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. The reactions of cold plasma with the surrounding atmosphere yield a variety of reactive species, which can define its effectiveness. While efficient development of cold plasma therapy requires kinetic models, model benchmarking needs empirical data. Experimental studies of the source of reactive species detected in aqueous solutions exposed to plasma are still scarce. Biomedical plasma is often operated with He or Ar feed gas, and a specific interest lies in investigation of the reactive species generated by plasma with various gas admixtures (O2, N2, air, H2O vapor, etc.) Such investigations are very complex due to difficulties in controlling the ambient atmosphere in contact with the plasma effluent. In this work, we addressed common issues of &#39;high&#39; voltage kHz frequency driven plasma jet experimental studies. A reactor was developed allowing the exclusion of ambient atmosphere from the plasma-liquid system. The system thus comprised the feed gas with admixtures and the components of the liquid sample. This controlled atmosphere allowed the investigation of the source of the reactive oxygen species induced in aqueous solutions by He-water vapor plasma. The use of isotopically labelled water allowed distinguishing between the species originating in the gas phase and those formed in the liquid. The plasma equipment was contained inside a Faraday cage to eliminate possible influence of any external field. The setup is versatile and can aid in further understanding the cold plasma-liquid interactions chemistry.

An experimental setup was created for the helium-operated kHz frequency plasma jet. The setup includes a cage for the plasma power supply and jet and an in-house built reactor to monitor plasma-induced reactive species without the interference of the ambient atmosphere.

Una configurazione plasma a pressione atmosferica per Indagare sulla formazione reattiva Specie

Non-thermal atmospheric pressure (&#39;cold&#39;) plasmas have received increased attention in recent years due to their significant biomedical potential. ...

Spark Plasma Sintering Apparatus Used for the Formation of Strontium Titanate Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with one twist grain boundary. This apparatus utilizes high uniaxial pressure and a pulsed direct current for rapid consolidation of material. Diffusion bonding of strontium titanate bicrystals without fracture, in a spark plasma sintering apparatus, is possible at high pressures due to the unusual temperature dependent plasticity behavior of strontium titanate. We demonstrate a method for the successful formation of bicrystals at accelerated time scales and lower temperatures in a spark plasma sintering apparatus compared to bicrystals formed by conventional diffusion bonding parameters. Bond quality was verified by scanning electron microscopy. A clean and atomically abrupt interface containing no secondary phases was observed using transmission electron microscopy techniques. Local changes in bonding across the boundary was characterized by simultaneous scanning transmission electron microscopy and spatially resolved electron energy-loss spectroscopy.

A viable technique for the formation of strontium titanate bicrystals at high pressure and fast heating rate via the spark plasma sintering apparatus is developed.

Spark Plasma Sintering apparecchio utilizzato per la formazione di titanato di stronzio Bicrystals

A spark plasma sintering apparatus was used as a novel method for diffusion bonding of two single crystals of strontium titanate to form bicrystals with ...

L'applicazione di X-ray Imaging cristallo Spettroscopia per l'uso come ad alta temperatura del plasma di diagnostica

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