المؤلفون: Barbisan, M., Delogu, R. S., Pimazzoni, A., Poggi, C., Ugoletti, M., Cavenago, M.

المصدر: IEEE Transactions on Plasma Science, vol. 50, no. 11, pp. 3859-3864, Nov. 2022

مصطلحات موضوعية: Physics - Plasma Physics, Physics - Accelerator Physics

الوصف: The compact radio frequency negative ion source NIO1 (Negative Ion Optimization phase 1) has been designed, built and operated by Consorzio RFX and INFN-LNL in order to study and optimize the production and acceleration of H- ions in continuous operation. In 2020 Cs was evaporated in the source to increase the total extracted ion current. After an initial reduction of extracted electron to ion ratio and subsequently an increase of extracted negative ion current, the source performances progressively worsened, because of the excessive amount of Cs evaporated in the source; the extracted electron to ion ratio increased from below 1 to more than 10, while ion current density reduced from max. 67 A/m2 ion current to not more than 30 A/m2). The paper presents the experimental observations collected during Cs evaporation (reduction of plasma light, Cs emission and H$\beta$/H$\gamma$ ratio, etc.) that can help stopping the process before an excessive amount of Cs is introduced in the source. The paper also reports the cleaning techniques tested to remove the Cs excess by the action of hydrogen or argon plasmas; while argon was predictably more effective in surface sputtering, a 3 h Ar plasma treatment was not sufficient to recover from overcesiation.
Comment: 6 pages, 5 figures. Accepted manuscript of a published paper

الوصول الحر: http://arxiv.org/abs/2308.15328Test

المؤلفون: Shepherd, A., Patton, T., Pimazzoni, A., Pouradier-Duteil, B., Garola, A. Rigoni, Sartori, E., Ugoletti, M., Serianni, G.

مصطلحات موضوعية: Physics - Accelerator Physics, Physics - Plasma Physics

الوصف: For negative ion beam sources there are several methods of measuring the accelerated beam current, most commonly electrical measurements at the power supply and calorimetric measurements. On SPIDER, the ITER Heating Neutral Beam full-scale beam source prototype, electrical measurements at the acceleration grid power supply (AGPS) are complemented by polarizing the diagnostic calorimeter STRIKE to provide an additional electrical measurement of the accelerated current. This is in addition to the calorimetric measurements provided by STRIKE. These diagnostics give differing measurements of the beam current. Exploiting the reduced number of open apertures on SPIDER a new beam diagnostic has been installed to measure the individual beamlet currents directly. The so called Beamlet Current Monitor (BCM) has been used to measure the current of five beamlets during the most recent SPIDER campaign. This work compares the BCM current to the electrical measurements at the AGPS and STRIKE. The average BCM current agrees well with the STRIKE electrical measurements, indicating that the AGPS overestimates the beam current. The individual beamlets are compared to the STRIKE calorimetric measurements, showing similar current trends with the source parameters.

الوصول الحر: http://arxiv.org/abs/2305.18001Test

المؤلفون: Maistrello, Alberto, Agostini, Matteo, Bigi, Marco, Brombin, Matteo, Dan, Mattia, Casagrande, Riccardo, De Nardi, Marco, Ferro, Alberto, Gaio, Elena, Jain, Palak, Lunardon, Francesco, Marconato, Nicolò, Marcuzzi, Diego, Recchia, Mauro, Patton, Tommaso, Pavei, Mauro, Santoro, Francesco, Toigo, Vanni, Zanotto, Loris, Barbisan, Marco, Baseggio, Lucio, Bernardi, Marco, Berton, Giovanni, Boldrin, Marco, Bello, Samuele Dal, Fasolo, Daniele, Franchin, Luca, Ghiraldelli, Raffaele, Grando, Luca, Milazzo, Ruggero, Pimazzoni, Antonio, Rigoni, Andrea, Sartori, Emanuele, Serianni, Gianluigi, Shepherd, Alastair, Ugoletti, Margherita, Zaniol, Barbara, Zella, Daniele, Zerbetto, Enrico, Decamps, Hans, Rotti, Chandramouli, Veltri, Pierluigi

المصدر: Fusion Engineering and Design, vol. 190, pages 113510, year 2023, issn 0920-3796

مصطلحات موضوعية: Physics - Plasma Physics, Physics - Instrumentation and Detectors

الوصف: SPIDER is the full-scale prototype of the ion source of the ITER Heating Neutral Beam Injector, where negative ions of Hydrogen or Deuterium are produced by a RF generated plasma and accelerated with a set of grids up to ~100 keV. The Power Supply System is composed of high voltage dc power supplies capable of handling frequent grid breakdowns, high current dc generators for the magnetic filter field and RF generators for the plasma generation. During the first 3 years of SPIDER operation different electrical issues were discovered, understood and addressed thanks to deep analyses of the experimental results supported by modelling activities. The paper gives an overview on the observed phenomena and relevant analyses to understand them, on the effectiveness of the short-term modifications provided to SPIDER to face the encountered issues and on the design principle of long-term solutions to be introduced during the currently ongoing long shutdown.
Comment: 8 pages, 12 figures. Presented at SOFT 2022

الوصول الحر: http://arxiv.org/abs/2304.02294Test

المؤلفون: Marcuzzi, D., Toigo, V., Boldrin, M., Chitarin, G., Bello, S. Dal, Grando, L., Luchetta, A., Pasqualotto, R., Pavei, M., Serianni, G., Zanotto, L., Agnello, R., Agostinetti, P., Agostini, M., Aprile, D., Barbisan, M., Battistella, M., Berton, G., Bigi, M., Brombin, M., Candela, V., Candeloro, V., Canton, A., Casagrande, R., Cavallini, C., Cavazzana, R., Cordaro, L., Cruz, N., Palma, M. Dalla, Dan, M., De Lorenzi, A., Delogu, R., De Muri, M., De Nardi, M., Denizeau, S., Fadone, M., Fellin, F., Ferro, A., Gaio, E., Gasparrini, C., Gnesotto, F., Jain, P., La Rosa, A., Lopez-Bruna, D., Lorenzini, R., Maistrello, A., Manduchi, G., Manfrin, S., Marconato, N., Mario, I., Martini, G., Milazzo, R., Patton, T., Peruzzo, S., Pilan, N., Pimazzoni, A., Poggi, C., Pomaro, N., Pouradier-Duteil, B., Recchia, M., Rigoni-Garola, A., Rizzetto, D., Rizzolo, A., Santoro, F., Sartori, E., Segalini, B., Shepherd, A., Siragusa, M., Sonato, P., Sottocornola, A., Spada, E., Spagnolo, S., Spolaore, M., Taliercio, C., Tinti, P., Tomsič, P., Trevisan, L., Ugoletti, M., Valente, M., Valisa, M., Veronese, F., Vignando, M., Zaccaria, P., Zagorski, R., Zaniol, B., Zaupa, M., Zuin, M., Cavenago, M., Boilson, D., Rotti, C., Decamps, H., Geli, F., Sharma, A., Veltri, P., Zacks, J., Simon, M., Paolucci, F., Garbuglia, A., Gutierrez, D., Masiello, A., Mico, G., Labate, C., Readman, P., Bragulat, E., Bailly-Maitre, L., Gomez, G., Kouzmenko, G., Albajar, F., Kashiwagi, M., Tobari, H., Kojima, A., Murayama, M., Hatakeyama, S., Oshita, E., Maejima, T., Shibata, N., Yamashita, Y., Watanabe, K., Singh, N. P., Singh, M. J., Dhola, H., Fantz, U., Heinemann, B., Wimmer, C., Wünderlich, D., Tsumori, K., Croci, G., Gorini, G., Muraro, A., Rebai, M., Tardocchi, M., Giacomelli, L., Rigamonti, D., Taccogna, F., Bruno, D., Rutigliano, M., Longo, S., Deambrosis, S., Miorin, E., Montagner, F., Tonti, A., Panin, F.

المصدر: Fusion Engineering and Design 191 (2023) 113590

مصطلحات موضوعية: Physics - Plasma Physics, Physics - Accelerator Physics

الوصف: ITER envisages the use of two heating neutral beam injectors plus an optional one as part of the auxiliary heating and current drive system. The 16.5 MW expected neutral beam power per injector is several notches higher than worldwide existing facilities. A Neutral Beam Test Facility (NBTF) was established at Consorzio RFX, exploiting the synergy of two test beds, SPIDER and MITICA. SPIDER is dedicated to developing and characterizing large efficient negative ion sources at relevant parameters in ITER-like conditions: source and accelerator located in the same vacuum where the beam propagates, immunity to electromagnetic interferences of multiple radio-frequency (RF) antennas, avoidance of RF-induced discharges on the outside of the source. Three years of experiments on SPIDER have addressed to the necessary design modifications to enable full performances. The source is presently under a long shut-down phase to incorporate learnings from the experimental campaign. Parallelly, developments on MITICA, the full-scale prototype of the ITER NBI featuring a 1 MV accelerator and ion neutralization, are underway including manufacturing of in-vessel components, while power supplies and auxiliary plants are already under final testing and commissioning. Integration, commissioning and tests of the 1MV power supplies are essential for this first-of-kind system, unparalleled both in research and industry field. The integrated test to confirm 1MV output by combining invertor systems, DC generators and transmission lines extracted errors/accidents in some components. To realize a concrete system for ITER, solutions for the repair and the improvement of the system were developed. Hence, NBTF is emerging as a necessary facility, due to the large gap with existing injectors, effectively dedicated to identify issues and find solutions to enable successful ITER NBI operations in a time bound fashion.

الوصول الحر: http://arxiv.org/abs/2304.01692Test

المؤلفون: Poggi, Carlo, Spolaore, Monica, Barbisan, Marco, Brombin, Matteo, Cavazzana, Roberto, Marconato, Nicolò, Pasqualotto, Roberto, Pimazzoni, Antonio, Sartori, Emanuele, Serianni, Gianluigi

مصطلحات موضوعية: Physics - Plasma Physics, Physics - Accelerator Physics

الوصف: Neutral Beam Injectors (NBIs) based on negative ions are the workhorses of future fusion reactors, such as ITER, which they are expected to provide with up to \SI{33}{MW} of power to heat the fusion plasma. The negative hydrogen ions are extracted from a RF plasma, in which a magnetic filter field cools down the electrons reaching the so-called expansion region and allows the formation of negative ions near the apertures in the plasma grid. To further improve the production of negative ions, cesium is usually evaporated inside the source and deposited onto the plasma walls, reducing the work function of the surfaces. This dramatically increases the density of negative hydrogen ions near the surfaces, causing the transition to an electronegative plasma in the vicinity of the plasma grid. This condition can be observed with Langmuir probes, which can then be used to provide a local meaurement of negative ion density in the ion source. In this paper we use the measurements provided by the Langmuir probe sensors embedded in the plasma grid of SPIDER, the prototype ion source of ITER NBIs, to determine the density of negative ions. A fitting method based on the determination of the collection area of the different plasma species is proposed and adapted to SPIDER experimental condition, taking into account the shape of the probes and the local topology of the magnetic field. The method is then applied to the experimental data, determining the densities of the positive and negative ions and of the electrons during a plasma pulse. Finally, a vertical array of four probes in the plasma grid is used to assess the vertical profile of plasma parameters.
Comment: 12 pages, 7 figures, contributed paper to the NIBS 22 conference. Submitted to Journal of Instrumentation

الوصول الحر: http://arxiv.org/abs/2302.12116Test

المؤلفون: Barbisan, M., Agnello, R., Cavenago, M., Delogu, R. S., Pimazzoni, A., Balconi, L., Barbato, P., Baseggio, L., Castagni, A., Duteil, B. Pouradier, Franchin, L., Laterza, B., Molon, F., Maniero, M., Migliorato, L., Milazzo, R., Passalacqua, G., Poggi, C., Ravarotto, D., Rizzieri, R., Romanato, L., Rossetto, F., Trevisan, L, Ugoletti, M., Zaniol, B., Zucchetti, S.

المصدر: JINST 18 C09002 (2023)

مصطلحات موضوعية: Physics - Plasma Physics, Physics - Accelerator Physics

الوصف: Consorzio RFX and INFN-LNL have designed, built and operated the compact radiofrequency negative ion source NIO1 (Negative Ion Optimization phase 1) with the aim of studying the production and acceleration of H- ions. In particular, NIO1 was designed to keep plasma generation and beam extraction continuously active for several hours. Since 2020 the production of negative ions at the plasma grid (the first grid of the acceleration system) has been enhanced by a Cs layer, deposited though active Cs evaporation in the source volume. For the negative ion sources applied to fusion neutral beam injectors, it is essential to keep the beam current and the fraction of co-extracted electrons stable for at least 1 h, against the consequences of Cs sputtering and redistribution operated by the plasma. The paper presents the latest results of the NIO1 source, in terms of caesiation process and beam performances during continuous (6{\div}7 h) plasma pulses. Due to the small dimensions of the NIO1 source (20 x (diam.)10 cm), the Cs density in the volume is high (10^15 \div 10^16 m^-3) and dominated by plasma-wall interaction. The maximum beam current density and minimum fraction of co-extracted electrons were respectively about 30 A/m^2 and 2. Similarly to what done in other negative ion sources, the plasma grid temperature in NIO1 was raised for the first time, up to 80 {\deg}C, although this led to a minimal improvement of the beam current and to an increase of the co-extracted electron current.
Comment: 11 pages, 7 figures. Contributed paper for the 8th International symposium on Negative Ions, Beams and Sources - NIBS'22. Revision 1 of the preprint under evaluation at Journal of Instrumentation (JINST)

الوصول الحر: http://arxiv.org/abs/2212.05801Test

المؤلفون: Shepherd, A, Patton, T, Duteil, BP, Pimazzoni, A, Garola, AR, Sartori, E

المساهمون: Shepherd, A, Patton, T, Duteil, Bp, Pimazzoni, A, Garola, Ar, Sartori, E

مصطلحات موضوعية: SPIDER, Negative-ion source, Beam current, Beam optic, Beam uniformity

الوصف: The ITER Heating Neutral Beam (HNB) source prototype SPIDER (Source for the Production of Ions of Deuterium Extracted from a Radio frequency plasma), hosted at the Neutral Beam Test Facility (NBTF) in Padova, Italy, has recently started operating with evaporated caesium in the source. This moves the primary symbolscript production mechanism from volume to surface processes, increasing the extracted symbolscript current while decreasing the co-extracted electron current. As in volume operation, the beam exhibits inhomogeneities across the vertical profile due to magnetic drifts, a result of the transverse filter field, which is vital for reducing the electron temperature near the extraction region. To minimise the occurrence of electrical discharges, SPIDER has been operated with a diminished number of extraction apertures to minimise the vessel pressure/ion source pressure ratio by means of a mask, which reduces the gas flow conductance between the source and the vessel. Therefore, it has been possible to directly measure the current of individual beamlets, due to the increased room between the beamlets, using the non-invasive Beamlet Current Monitor (BCM) diagnostic. Using measurements of five individual beamlets the homogeneity of the SPIDER symbolscript beam has been assessed, in a range of operating conditions with caesium in the source. The dependence of the beam homogeneity on source parameters (bias, filter field, RF power) has been observed, while increasing the Cs evaporation rate and unbalancing the power of the RF generators have proven to be effective at mitigating the beam inhomogeneity.

العلاقة: info:eu-repo/semantics/altIdentifier/wos/WOS:000953142400001; volume:192; firstpage:113599; journal:FUSION ENGINEERING AND DESIGN; https://hdl.handle.net/11577/3480033Test; info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85149183310

الإتاحة: https://doi.org/10.1016/j.fusengdes.2023.113599Test
https://hdl.handle.net/11577/3480033Test

المؤلفون: Barbisan M., Agnello R., Cavenago M., Delogu R., Pimazzoni A., Balconi L., Barbato P., Baseggio L., Castagni A., Pouradier Duteil B., Franchin L., Laterza B., Molon F., Maniero M., Migliorato L., Milazzo R., Passalacqua G., Poggi C., Ravarotto D., Rizzieri R., Romanato L., Rossetto F., Trevisan L., Ugoletti M., Zaniol B., Zucchetti S.

المساهمون: M. Barbisan, R. Agnello, M. Cavenago, R. Delogu, A. Pimazzoni, L. Balconi, P. Barbato, L. Baseggio, A. Castagni, B. Pouradier Duteil, L. Franchin, B. Laterza, F. Molon, M. Maniero, L. Migliorato, R. Milazzo, G. Passalacqua, C. Poggi, D. Ravarotto, R. Rizzieri, L. Romanato, F. Rossetto, L. Trevisan, M. Ugoletti, B. Zaniol, S. Zucchetti

مصطلحات موضوعية: Ion sources (positive ions, negative ions, electron cyclotron resonance (ECR), electron beam (EBIS)), Plasma diagnostics - interferometry, spectroscopy and imaging, Plasma generation (laser-produced, RF, x ray-produced), Settore FIS/03 - Fisica della Materia

الوصف: Consorzio RFX and INFN-LNL have designed, built and operated the compact radiofrequency negative ion source NIO1 (Negative Ion Optimization phase 1) with the aim of studying the production and acceleration of H- ions. In particular, NIO1 was designed to keep plasma generation and beam extraction continuously active for several hours. Since 2020 the production of negative ions at the plasma grid (the first grid of the acceleration system) has been enhanced by a Cs layer, deposited though active Cs evaporation in the source volume. For the negative ion sources applied to fusion neutral beam injectors, it is essential to keep the beam current and the fraction of co-extracted electrons stable for at least 1 h, against the consequences of Cs sputtering and redistribution operated by the plasma. The paper presents the latest results of the NIO1 source, in terms of caesiation process and beam performances during continuous (6 ÷ 7 h) plasma pulses. Due to the small dimensions of the NIO1 source (20 cm×∅10 cm), the Cs density in the volume is high (1015 ÷ 1016 m-3) and dominated by plasma-wall interaction. The maximum beam current density and minimum fraction of co-extracted electrons were respectively about 30 A/m2 and 2. Similarly to what done in other negative ion sources, the plasma grid temperature in NIO1 was raised for the first time, up to 80 °C, although this led to a minimal improvement of the beam current and to an increase of the co-extracted electron current.

العلاقة: info:eu-repo/semantics/altIdentifier/wos/WOS:001070815900001; volume:18; issue:9; firstpage:1; lastpage:11; numberofpages:11; journal:JOURNAL OF INSTRUMENTATION; https://hdl.handle.net/2434/1030370Test; info:eu-repo/semantics/altIdentifier/scopus/2-s2.0-85170825582

الإتاحة: https://doi.org/10.1088/1748-0221/18/09/C09002Test
https://hdl.handle.net/2434/1030370Test

المؤلفون: Giacomo Vezzani, Silvia Pimazzoni, Rossella Ferranti, Stefano Calò, Giuseppina Monda, Diego Amendola, Elisabetta Frigimelica, Domenico Maione, Mirko Cortese, Marcello Merola

المصدر: Frontiers in Microbiology, Vol 13 (2023)

مصطلحات موضوعية: human cytomegalovirus, viral Fcγ-binding proteins, gp68 (UL119), gp34 (RL11), gp95 (RL12), HCMV neutralizing antibodies, Microbiology, QR1-502

الوصف: Human cytomegaloviruses (HCMVs) employ many different mechanisms to escape and subvert the host immune system, including expression of the viral IgG Fcγ receptors (vFcγRs) RL11 (gp34), RL12 (gp95), RL13 (gpRL13), and UL119 (gp68) gene products. The role of vFcγRs in HCMV pathogenesis has been reported to operate in infected cells by interfering with IgG-mediated effector functions. We found that gp34 and gp68 are envelope proteins that bind and internalize human IgGs on the surface of infected cells. Internalized IgGs are then transported on the envelope of viral particles in a vFcR-dependent mechanism. This mechanism is also responsible for the incorporation on the virions of the anti-gH neutralizing antibody MSL-109. Intriguingly, we show that gp68 is responsible for MSL-109 incorporation, but it is dispensable for other anti-HCMV antibodies that do not need this function to be transported on mature virions. HCMV-infected cells grown in presence of anti-HCMV monoclonal antibodies generate a viral progeny still infective and possible to be neutralized. This is the first example of a virus carrying neutralizing IgGs on its surface and their possible role is discussed.

وصف الملف: electronic resource

العلاقة: https://www.frontiersin.org/articles/10.3389/fmicb.2022.1106401/fullTest; https://doaj.org/toc/1664-302XTest

الوصول الحر: https://doaj.org/article/7b30b5c32fa94b47aa99ed654595fd68Test

المؤلفون: Tommaso Patton, Alastair Shepherd, Basile Pouradier Duteil, Andrea Rigoni Garola, Matteo Brombin, Valeria Candeloro, Gabriele Manduchi, Mauro Pavei, Roberto Pasqualotto, Antonio Pimazzoni, Marco Siragusa, Gianluigi Serianni, Emanuele Sartori, Cesare Taliercio, Paolo Barbato, Vannino Cervaro, Raffaele Ghiraldelli, Bruno Laterza, Federico Rossetto

المصدر: Sensors; Volume 23; Issue 13; Pages: 6211

مصطلحات موضوعية: neutral beam injector, negative ions accelerator, beam fluctuations, SPIDER, ITER

الوصف: Stable and uniform beams with low divergence are required in particle accelerators; therefore, beyond the accelerated current, measuring the beam current spatial uniformity and stability over time is necessary to assess the beam performance, since these parameters affect the perveance and thus the beam optics. For high-power beams operating with long pulses, it is convenient to directly measure these current parameters with a non-intercepting system due to the heat management requirement. Such a system needs to be capable of operating in a vacuum in the presence of strong electromagnetic fields and overvoltages, due to electrical breakdowns in the accelerator. Finally, the measure of the beam current needs to be efficiently integrated into a pulse file with the other relevant plant parameters to allow the data analyses required for beam optimization. This paper describes the development, design and commissioning of such a non-intercepting system, the so-called beamlet current monitor (BCM), aimed to directly measure the electric current of a particle beam. In particular, the layout of the system was adapted to the SPIDER experiment, the ion source (IS) prototype of the heating neutral beam injectors (HNB) for the ITER fusion reactor. The diagnostic is suitable to provide the electric current of five beamlets from DC up to 10 MHz.

وصف الملف: application/pdf

العلاقة: Remote Sensors; https://dx.doi.org/10.3390/s23136211Test

الإتاحة: https://doi.org/10.3390/s23136211Test