Analysis of fusion dust particles

Čestice fuzijske prašine iz tokamaka JET analizirane su snopom iona helija-3 energije 4 MeVa. Kako bi se našli tragovi fuzijskog goriva korištene su analitičke metode NRA i PIXE. Poseban naglasak je stavljen na geometriju eksperimenta zbog velikog prostornog kuta NRA detektora. Analiza je pokazala da su čestice fuzijske prašine sačinjene od volframa, inkonela (nikla, željeza, kroma, niobija, molibdena), deuterija, berilija, dušika itd. Većina čestica je podrijetlom iz dijelova reaktorske komore koji su izloženi plazmi, no dio ih je nefuzijskog podrijetla. Potonje su vjerojatno nastale kontaminacijom tokom održavanja.Fusion dust particles from the JET tokamak were analyzed using a 4 MeV helium-3 microbeam. NRA and PIXE methods were used with the aim of finding residual fusion fuel (deuterium) in fusion dust particles. Particular emphasis has been put on the geometry of the experiment due to the large solid angle of the surface barrier detector used in the analysis. The analysis has shown that the particles are comprised of tungsten, inconel (nickel, iron, chromium, niobium, molibdenum), deuterium, beryllium, nitrogen, etc. While the most of the particles are a result of plasma interacting with plasma-facing components, some of them are clearly non-fusion in origin. The latter particles are most probably the result of maintenance procedures

Analysis of fusion dust particles

Čestice fuzijske prašine iz tokamaka JET analizirane su snopom iona helija-3 energije 4 MeVa. Kako bi se našli tragovi fuzijskog goriva korištene su analitičke metode NRA i PIXE. Poseban naglasak je stavljen na geometriju eksperimenta zbog velikog prostornog kuta NRA detektora. Analiza je pokazala da su čestice fuzijske prašine sačinjene od volframa, inkonela (nikla, željeza, kroma, niobija, molibdena), deuterija, berilija, dušika itd. Većina čestica je podrijetlom iz dijelova reaktorske komore koji su izloženi plazmi, no dio ih je nefuzijskog podrijetla. Potonje su vjerojatno nastale kontaminacijom tokom održavanja.Fusion dust particles from the JET tokamak were analyzed using a 4 MeV helium-3 microbeam. NRA and PIXE methods were used with the aim of finding residual fusion fuel (deuterium) in fusion dust particles. Particular emphasis has been put on the geometry of the experiment due to the large solid angle of the surface barrier detector used in the analysis. The analysis has shown that the particles are comprised of tungsten, inconel (nickel, iron, chromium, niobium, molibdenum), deuterium, beryllium, nitrogen, etc. While the most of the particles are a result of plasma interacting with plasma-facing components, some of them are clearly non-fusion in origin. The latter particles are most probably the result of maintenance procedures

Interpretative and predictive modelling of Joint European Torus collisionality scans

Transport modelling of Joint European Torus (JET) dimensionless collisionality scaling experiments in various operational scenarios is presented. Interpretative simulations at a fixed radial position are combined with predictive JETTO simulations of temperatures and densities, using the TGLF transport model. The model includes electromagnetic effects and collisions as well as (E)over-right-arrow x (b)over-right-arrow shear in Miller geometry. Focus is on particle transport and the role of the neutral beam injection (NBI) particle source for the density peaking. The experimental 3-point collisionality scans include L-mode, and H-mode (D and H and higher beta D plasma) plasmas in a total of 12 discharges. Experimental results presented in (Tala et al 2017 44th EPS Conf.) indicate that for the H-mode scans, the NBI particle source plays an important role for the density peaking, whereas for the L-mode scan, the influence of the particle source is small. In general, both the interpretative and predictive transport simulations support the experimental conclusions on the role of the NBI particle source for the 12 JET discharges.Peer reviewe

Ion Microbeam Analyses of Dust Particles and Codeposits from JET with the ITER-Like Wall

Generation of metal dust in the JET tokamak with the ITER-like wall (ILW) is a topic of vital interest to next-step fusion devices because of safety issues with plasma operation. Simultaneous Nuclear Reaction Analysis (NRA) and Particle-Induced X-ray Emission (PIXE) with a focused four MeV 3He microbeam was used to determine the composition of dust particles related to the JET operation with the ILW. The focus was on “Be-rich particles” collected from the deposition zone on the inner divertor tile. The particles found are composed of a mix of codeposited species up to 120 μm in size with a thickness of 30–40 μm. The main constituents are D from the fusion fuel, Be and W from the main plasma-facing components, and Ni and Cr from the Inconel grills of the antennas for auxiliary plasma heating. Elemental concentrations were estimated by iterative NRA-PIXE analysis. Two types of dust particles were found: (i) larger Be-rich particles with Be concentrations above 90 at% with a deuterium presence of up to 3.4 at% and containing Ni (1–3 at%), Cr (0.4–0.8 at%), W (0.2–0.9 at%), Fe (0.3–0.6 at%), and Cu and Ti in lower concentrations and (ii) small particles rich in Al and/or Si that were in some cases accompanied by other elements, such as Fe, Cu, or Ti or W and Mo

Traffic Load Analysis on the HSS Element in LTE Networks

Pristupna mreža LTE (engl. Long Term Evolution) u odnosu na prethodne generacije pokretnih mreža uvodi poboljšanje u prijenosnoj brzini, smanjenju kašnjenja i kvaliteti usluge. Njena glavna karakteristika je ostvarivanje komunikacije bazirane u potpunosti na protokolu IP. Takvim se pristupom mrežnim korisnicima dopušta korištenje raznovrsnih multimedijskih usluga poput chatting aplikacije ili konferencijskog poziva. Arhitekturu LTE mreže možemo podijeliti na tri djela, pristupni (engl. Access), jezgreni EPC (engl. Evolved Packet Core) i upravljački (engl. Control). U upravljačkoj domeni nalazi se zasebna mreža IMS (engl. IP multimedia subsystem) koja pruža raznovrsne multimedijske usluge. Organizacija 3GPP (engl. 3rd Generation Partnership Project) nadležna je za standardizaciju sučelja u mrežama LTE i IMS. Nadalje, logika usluga implementira se na komponenti AS (engl. Application Server), a baza podataka u kojoj se nalaze pretplatnički podatci naziva se HSS (engl. Home Subscriber Server). Komunikacija između te dvije komponente ostvaruje se standardiziranim sučeljem Sh koje koristi signalizacijski protokol Diameter. U ovome radu analizirane su karakteristike komponente HSS s obzirom na sljedeće modele prometnih opterećenja: Poissonovo, eksponencijalno, linearno te uniformno. Testiranje se vršilo s ciljem otkrivanja točke ispada komponente HSS. Također, u svrhu testiranja napravljena je programska potpora koja omogućava implementaciju odabranih modela opterećenja. Sve komponente IMS podsustava nalaze se u laboratoriju kompanije SIEMENS C.V.C. smještene u Zagrebu. Razmatranjem dobivenih rezultata ustanovilo se da eksponencijalni model u najvišoj mjeri opterećuje komponentu HSS. Učestale promjene u frekvenciji slanja za posljedicu unose pogreške u odzivu protokola Diameter, kao i veliko vrijeme kašnjenja. U trenutku kada je HSS opterećen na ostalim sučeljima, ovaj problem može predstavljati kritičan slučaj. Rezultat takve okolnosti bilo bi smanjenje brzine obrade i povećanje broja neispravno obrađenih poruka.The LTE network, in comparison with earlier generations of mobile networks, introduces faster data rates, lower latency and higher quality of service. The main feature of such architecture is to provide communication on common IP-based protocols. This approach allows network users to use various multimedia services such as chatting application or conference calls. The architecture of the LTE network is divided into three parts: the access, the EPC (Evolved Packet Core) and the control domain. The IMS (IP multimedia subsystem) is located in the control domain and provides various types of multimedia services to end users. The interconnections between network components in the LTE and IMS are standardized under the 3GPP (3rd generation partnership project) organization. Furthermore, the service logic is deployed in the AS (Application Server), and the HSS (Home Subscriber Server) is the master database that contains the subscriber related data. The communication between the HSS and the AS is realized via the standardized Sh interface. The signalization Diameter protocol is used to provide this communication. This paper analyzes the characteristics of the HSS when it is overloaded with the following traffic models: Poisson, exponential, linear and uniform. Test cases were performed in order to determinate how much traffic load the HSS can handle. The task was also to develop a software that enables the implementation of desired traffic models. Furthermore, all IMS components are located at the Siemens CVC facility in Zagreb. The results of testing show that the exponential model overloads the HSS in the highest rate. Frequent changes in the frequency of sending causes large delay times and adds Diameter errors. This problem can be critical when the HSS is also overloaded on other interfaces. The results would be lower processing speeds and a larger amount of errors

Traffic Load Analysis on the HSS Element in LTE Networks

Pristupna mreža LTE (engl. Long Term Evolution) u odnosu na prethodne generacije pokretnih mreža uvodi poboljšanje u prijenosnoj brzini, smanjenju kašnjenja i kvaliteti usluge. Njena glavna karakteristika je ostvarivanje komunikacije bazirane u potpunosti na protokolu IP. Takvim se pristupom mrežnim korisnicima dopušta korištenje raznovrsnih multimedijskih usluga poput chatting aplikacije ili konferencijskog poziva. Arhitekturu LTE mreže možemo podijeliti na tri djela, pristupni (engl. Access), jezgreni EPC (engl. Evolved Packet Core) i upravljački (engl. Control). U upravljačkoj domeni nalazi se zasebna mreža IMS (engl. IP multimedia subsystem) koja pruža raznovrsne multimedijske usluge. Organizacija 3GPP (engl. 3rd Generation Partnership Project) nadležna je za standardizaciju sučelja u mrežama LTE i IMS. Nadalje, logika usluga implementira se na komponenti AS (engl. Application Server), a baza podataka u kojoj se nalaze pretplatnički podatci naziva se HSS (engl. Home Subscriber Server). Komunikacija između te dvije komponente ostvaruje se standardiziranim sučeljem Sh koje koristi signalizacijski protokol Diameter. U ovome radu analizirane su karakteristike komponente HSS s obzirom na sljedeće modele prometnih opterećenja: Poissonovo, eksponencijalno, linearno te uniformno. Testiranje se vršilo s ciljem otkrivanja točke ispada komponente HSS. Također, u svrhu testiranja napravljena je programska potpora koja omogućava implementaciju odabranih modela opterećenja. Sve komponente IMS podsustava nalaze se u laboratoriju kompanije SIEMENS C.V.C. smještene u Zagrebu. Razmatranjem dobivenih rezultata ustanovilo se da eksponencijalni model u najvišoj mjeri opterećuje komponentu HSS. Učestale promjene u frekvenciji slanja za posljedicu unose pogreške u odzivu protokola Diameter, kao i veliko vrijeme kašnjenja. U trenutku kada je HSS opterećen na ostalim sučeljima, ovaj problem može predstavljati kritičan slučaj. Rezultat takve okolnosti bilo bi smanjenje brzine obrade i povećanje broja neispravno obrađenih poruka.The LTE network, in comparison with earlier generations of mobile networks, introduces faster data rates, lower latency and higher quality of service. The main feature of such architecture is to provide communication on common IP-based protocols. This approach allows network users to use various multimedia services such as chatting application or conference calls. The architecture of the LTE network is divided into three parts: the access, the EPC (Evolved Packet Core) and the control domain. The IMS (IP multimedia subsystem) is located in the control domain and provides various types of multimedia services to end users. The interconnections between network components in the LTE and IMS are standardized under the 3GPP (3rd generation partnership project) organization. Furthermore, the service logic is deployed in the AS (Application Server), and the HSS (Home Subscriber Server) is the master database that contains the subscriber related data. The communication between the HSS and the AS is realized via the standardized Sh interface. The signalization Diameter protocol is used to provide this communication. This paper analyzes the characteristics of the HSS when it is overloaded with the following traffic models: Poisson, exponential, linear and uniform. Test cases were performed in order to determinate how much traffic load the HSS can handle. The task was also to develop a software that enables the implementation of desired traffic models. Furthermore, all IMS components are located at the Siemens CVC facility in Zagreb. The results of testing show that the exponential model overloads the HSS in the highest rate. Frequent changes in the frequency of sending causes large delay times and adds Diameter errors. This problem can be critical when the HSS is also overloaded on other interfaces. The results would be lower processing speeds and a larger amount of errors

Analysis of fusion dust particles

Čestice fuzijske prašine iz tokamaka JET analizirane su snopom iona helija-3 energije 4 MeVa. Kako bi se našli tragovi fuzijskog goriva korištene su analitičke metode NRA i PIXE. Poseban naglasak je stavljen na geometriju eksperimenta zbog velikog prostornog kuta NRA detektora. Analiza je pokazala da su čestice fuzijske prašine sačinjene od volframa, inkonela (nikla, željeza, kroma, niobija, molibdena), deuterija, berilija, dušika itd. Većina čestica je podrijetlom iz dijelova reaktorske komore koji su izloženi plazmi, no dio ih je nefuzijskog podrijetla. Potonje su vjerojatno nastale kontaminacijom tokom održavanja.Fusion dust particles from the JET tokamak were analyzed using a 4 MeV helium-3 microbeam. NRA and PIXE methods were used with the aim of finding residual fusion fuel (deuterium) in fusion dust particles. Particular emphasis has been put on the geometry of the experiment due to the large solid angle of the surface barrier detector used in the analysis. The analysis has shown that the particles are comprised of tungsten, inconel (nickel, iron, chromium, niobium, molibdenum), deuterium, beryllium, nitrogen, etc. While the most of the particles are a result of plasma interacting with plasma-facing components, some of them are clearly non-fusion in origin. The latter particles are most probably the result of maintenance procedures

Traffic Load Analysis on the HSS Element in LTE Networks

Pristupna mreža LTE (engl. Long Term Evolution) u odnosu na prethodne generacije pokretnih mreža uvodi poboljšanje u prijenosnoj brzini, smanjenju kašnjenja i kvaliteti usluge. Njena glavna karakteristika je ostvarivanje komunikacije bazirane u potpunosti na protokolu IP. Takvim se pristupom mrežnim korisnicima dopušta korištenje raznovrsnih multimedijskih usluga poput chatting aplikacije ili konferencijskog poziva. Arhitekturu LTE mreže možemo podijeliti na tri djela, pristupni (engl. Access), jezgreni EPC (engl. Evolved Packet Core) i upravljački (engl. Control). U upravljačkoj domeni nalazi se zasebna mreža IMS (engl. IP multimedia subsystem) koja pruža raznovrsne multimedijske usluge. Organizacija 3GPP (engl. 3rd Generation Partnership Project) nadležna je za standardizaciju sučelja u mrežama LTE i IMS. Nadalje, logika usluga implementira se na komponenti AS (engl. Application Server), a baza podataka u kojoj se nalaze pretplatnički podatci naziva se HSS (engl. Home Subscriber Server). Komunikacija između te dvije komponente ostvaruje se standardiziranim sučeljem Sh koje koristi signalizacijski protokol Diameter. U ovome radu analizirane su karakteristike komponente HSS s obzirom na sljedeće modele prometnih opterećenja: Poissonovo, eksponencijalno, linearno te uniformno. Testiranje se vršilo s ciljem otkrivanja točke ispada komponente HSS. Također, u svrhu testiranja napravljena je programska potpora koja omogućava implementaciju odabranih modela opterećenja. Sve komponente IMS podsustava nalaze se u laboratoriju kompanije SIEMENS C.V.C. smještene u Zagrebu. Razmatranjem dobivenih rezultata ustanovilo se da eksponencijalni model u najvišoj mjeri opterećuje komponentu HSS. Učestale promjene u frekvenciji slanja za posljedicu unose pogreške u odzivu protokola Diameter, kao i veliko vrijeme kašnjenja. U trenutku kada je HSS opterećen na ostalim sučeljima, ovaj problem može predstavljati kritičan slučaj. Rezultat takve okolnosti bilo bi smanjenje brzine obrade i povećanje broja neispravno obrađenih poruka.The LTE network, in comparison with earlier generations of mobile networks, introduces faster data rates, lower latency and higher quality of service. The main feature of such architecture is to provide communication on common IP-based protocols. This approach allows network users to use various multimedia services such as chatting application or conference calls. The architecture of the LTE network is divided into three parts: the access, the EPC (Evolved Packet Core) and the control domain. The IMS (IP multimedia subsystem) is located in the control domain and provides various types of multimedia services to end users. The interconnections between network components in the LTE and IMS are standardized under the 3GPP (3rd generation partnership project) organization. Furthermore, the service logic is deployed in the AS (Application Server), and the HSS (Home Subscriber Server) is the master database that contains the subscriber related data. The communication between the HSS and the AS is realized via the standardized Sh interface. The signalization Diameter protocol is used to provide this communication. This paper analyzes the characteristics of the HSS when it is overloaded with the following traffic models: Poisson, exponential, linear and uniform. Test cases were performed in order to determinate how much traffic load the HSS can handle. The task was also to develop a software that enables the implementation of desired traffic models. Furthermore, all IMS components are located at the Siemens CVC facility in Zagreb. The results of testing show that the exponential model overloads the HSS in the highest rate. Frequent changes in the frequency of sending causes large delay times and adds Diameter errors. This problem can be critical when the HSS is also overloaded on other interfaces. The results would be lower processing speeds and a larger amount of errors

High temperature spherical nano-indentation of graphite crystals

Nano-indentation at temperatures up to 600 °C has been applied to the (0001) surface of highly oriented pyrolytic graphite using a spherical diamond tip (∼10 μm diameter). Cross-sectional observations of the indentations by dark field scanning transmission electron microscopy show an increased tendency at high temperature for inelastic deformation by buckling of the graphite crystals with kink formation