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In parallel to the developments dedicated to the ITER neutral beam (NB) system, CEA-IRFM with laboratories in France and Switzerland are studying the feasibility of a new generation of NB system able to provide heating and current drive for the future DEMOnstration fusion reactor. For the steady-state scenario, the NB system will have to provide a high NB power level with a high wall-plug efficiency ( ∼ 60%). Neutralization of the energetic negative ions by photodetachment (so called photoneutralization), if feasible, appears to be the ideal solution to meet these performances, in the sense that it could offer a high beam neutralization rate (>80%) and a wall-plug efficiency higher than 60%. The main challenge of this new injector concept is the achievement of a very high power photon flux which could be provided by 3 MW Fabry-Perot optical cavities implanted along the 1 MeV D− beam in the neutralizer stage. The beamline topology is tall and narrow to provide laminar ion beam sheets, which will be entirely illuminated by the intra-cavity photon beams propagating along the vertical axis. The paper describes the present R&D (experiments and modelling) addressing the development of a new ion source concept (Cybele source) which is based on a magnetized plasma column. Parametric studies of the source are performed using Langmuir probes in order to characterize and compare the plasma parameters in the source column with different plasma generators, such as filamented cathodes, radio-frequency driver and a helicon antenna specifically developed at SPC-EPFL satisfying the requirements for the Cybele (axial magnetic field of 10 mT, source operating pressure: 0.3 Pa in hydrogen or deuterium). The paper compares the performances of the three plasma generators. It is shown that the helicon plasma generator is a very promising candidate to provide an intense and uniform negative ion beam sheet.

The possibility of performing electron density and temperature measurements in a high power helicon plasma is a crucial issue in the framework of the AWAKE (Advanced WAKefield Experiment) project, which demonstrates acceleration of particles using$\\text{GeV}~\\text{m}^{-1}$electric fields in plasmas. For AWAKE, a helicon is currently envisaged as a candidate plasma source due to its capability for low electron and ion temperature, high electron density and production of an elongated plasma column. A plasma diagnostic to accurately determine the electron density in AWAKE regimes would be a valuable supporting tool. A demonstration Thomson scattering (TS) diagnostic was installed and successfully tested on the resonant antenna ion device (RAID) at the Swiss Plasma Center of Ecole Polytechnique Fédérale de Lausanne. RAID produces a helicon plasma column with characteristics similar to those of the AWAKE helicon source, and is therefore an optimal testbed for application to the AWAKE device. The spectrometer employed in RAID is based on polychromators which collect the light scattered by plasma electrons in spectrally filtered wavelength regions. Results from TS on RAID demonstrate conditions of electron density and temperature respectively of$n_{e}=1.10\\,(\\pm 0.19)\\times 10^{19}~\\text{m}^{-3}$and$T_{e}=2.3\\,(\\pm 0.6)~\\text{eV}$in a steady-state discharge in an Ar plasma with 5 kW of RF power. If the same polychromator system is used for AWAKE, where the electron density attained is$2\\times 10^{20}~\\text{m}^{-3}$, the contribution to measurement error due to coherent scattering is${\\sim}2.5\\,\\%$. Presented here are details of the TS diagnostic and the first tests in RAID, and the expectations for the system when employed on the AWAKE device.

Most countries around the world base their old-age pension programs largely on the pay-as-you-go defined benefit (PAYGO DB) model. However, due to a number of factors including population aging, the maturing of these schemes, rapidly increasing old-age pension costs, and the perceived need to become more competitive in international markets, many nations have become increasingly concerned about the present (or projected future) economic burden of paying for the pension benefits promised by these schemes. This concern has led policy makers to look for alternative models. One of the most innovative alternatives to emerge during the past ten years is the notional defined contribution (NDC) model. In this article we describe this model and discuss some of the implications of a shift to this model for women and low-wage workers. We conclude that in the industrial nations women and low-wage workers are likely to do less well with schemes based all or in part on the NDC model because such schemes are typically designed to be less redistributive (from higher to lower income groups) than the PAYGO DB schemes they will be replacing. However, in developing countries the reverse will often be true as the NDC schemes are likely to be replacing PAYGO DB schemes that tend to redistribute from low-income groups to higher income groups. Relative to funded DC schemes a major advantage of the NDC model is that it does not subject individual pension benefits to the volatility of financial markets. This issue is relevant to workers in both developed and developing nations, but it is a particularly important consideration in developing nations.

Since the signature of the ITER treaty in 2006, a new research programme targeting the emergence of a new generation of Neutral Beam (NB) system for the future fusion reactor (DEMO Tokamak) has been underway between several laboratories in Europe. The specifications required to operate a NB system on DEMO are very demanding: the system has to provide plasma heating, current drive and plasma control at a very high level of power (up to 150 MW) and energy (1 or 2 MeV), including high performances in term of wall-plug efficiency (\\(\\eta\\) > 60%), high availability and reliability. To this aim, a novel NB concept based on the photodetachment of the energetic negative ion beam is under study. The keystone of this new concept is the achievement of a photoneutralizer where a high power photon flux (~3 MW) generated within a Fabry Perot cavity will overlap, cross and partially photodetach the intense negative ion beam accelerated at high energy (1 or 2 MeV). The aspect ratio of the beam-line (source, accelerator, etc.) is specifically designed to maximize the overlap of the photon beam with the ion beam. It is shown that such a photoneutralized based NB system would have the capability to provide several tens of MW of D 0 per beam line with a wall-plug efficiency higher than 60%. A feasibility study of the concept has been launched between different laboratories to address the different physics aspects, i.e., negative ion source, plasma modelling, ion accelerator simulation, photoneutralization and high voltage holding under vacuum. The paper describes the present status of the project and the main achievements of the developments in laboratories.

A birdcage resonant helicon antenna is designed, mounted and tested in the toroidal device TORPEX. The birdcage resonant antenna is an alternative to the usual Boswell or half-helical antenna designs commonly used for \\(\\sim\\) 10 cm diameter helicon sources in low temperature plasma devices. The main advantage of the birdcage antenna lies in its resonant nature, which makes it easily operational even at large scales, an appealing feature for the TORPEX device whose poloidal cross section is 40 cm in diameter. With this antenna helicon waves are shown to be launched and sustained throughout the whole torus of TORPEX. The helicon waves can be launched at low power on a pre-existing magnetron-generated plasma with little effect on the density profiles. The birdcage antenna can also be used alone to produce plasma, which removes the constraint of a narrow range of applied magnetic fields required by the magnetron, opening the way to a new range of studies on TORPEX with the external magnetic field as a control parameter.

Most countries around the world base their oldage pension programs largely on the payasyougo defined benefit PAYGO DB model. However, due to a number of factors including population aging, the maturing of these schemes, rapidly increasing oldage pension costs, and the perceived need to become more competitive in international markets, many nations have become increasingly concerned about the present or projected future economic burden of paying for the pension benefits promised by these schemes. This concern has led policy makers to look for alternative models. One of the most innovative alternatives to emerge during the past ten years is the notional defined contribution NDC model. In this article we describe this model and discuss some of the implications of a shift to this model for women and lowwage workers. We conclude that in the industrial nations women and lowwage workers are likely to do less well with schemes based all or in part on the NDC model because such schemes are typically designed to be less redistributive from higher to lower income groups than the PAYGO DB schemes they will be replacing. However, in developing countries the reverse will often be true as the NDC schemes are likely to be replacing PAYGO DB schemes that tend to redistribute from lowincome groups to higher income groups. Relative to funded DC schemes a major advantage of the NDC model is that it does not subject individual pension benefits to the volatility of financial markets. This issue is relevant to workers in both developed and developing nations, but it is a particularly important consideration in developing nations.

In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from the Super Proton Synchrotron (SPS) at CERN. The angular distribution of the protons deflected due to SSM is a quantitative measure of the process, which agrees with simulations by the two-dimensional (axisymmetric) particle-in-cell code LCODE. Agreement is achieved for beam populations between \\(10^{11}\\) and \\(3 \\times 10^{11}\\) particles, various plasma density gradients (\\(-20 \\div 20\\%\\)) and two plasma densities (\\(2\\times 10^{14} \\text{cm}^{-3}\\) and \\(7 \\times 10^{14} \\text{cm}^{-3}\\)). The agreement is reached only in the case of a wide enough simulation box (at least five plasma wavelengths).

Resonant antennas are increasingly employed by the plasma industry, and the theory has now developed alongside the technological applications to the extent that it is timely to document the progress in this field to aid antenna design for future novel RF plasma sources. This reference text explains the complete theory of resonant antennas, from fundamental circuits to mutual partial inductance coupling with plasma. It describes industrial applications, and covers state-of-the-art research in helicon wave physics and sources with plasma diagnostics. The book is divided into four parts, covering resonant network antennas without plasma, antennas in magnetized and non-magnetized plasma, and finally, technology and future developments of resonant network antennas. Part of IOP Series in Plasma Physics.

Not all agricultural practices are sustainable; however, non-thermal plasma treatment of seeds may be an eco-friendly alternative to improve macroscopic plant growth parameters. Despite the numerous successful results of plasma-seed treatments reported in the literature, there is a large gap in our understanding of how non-thermal plasma treatments affect seeds, especially due to the plethora of physical, chemical, and biological variables. This study uses RNA sequencing to characterize the changes in gene transcription in Arabidopsis thaliana (L.) Heynh. seeds 6 days after exposure to surface dielectric barrier discharge plasma treatment. Here, we provide an overview of all pathways that are differentially expressed where few genes are upregulated and many genes are downregulated. Our results reveal that plasma treatment time is a parameter that can activate different pathways in plant defense. An 80 s treatment upregulates the glucosinolate pathway, a defense response to insects and herbivores to deter feeding, whereas a shorter treatment of 60 s upregulates the phenylpropanoid pathway, which reinforces the cell wall with lignin and produces antimicrobial compounds, a defense response to bacterial or fungal plant pathogens. It seems that plasma elicits a wounding response from the seed in addition to redox changes. This suggests that plasma treatment can be potentially applied in agriculture to protect plants against abiotic and biotic stresses without discharging residues into the environment.

Non-thermal plasma-seed treatments could be an environmentally friendly method to modulate plant properties. Since it remains unclear how plasmas affect seeds, RNA sequencing was used here to analyze gene transcription changes in 7-day-old Arabidopsis thaliana (L.) Heynh. seedlings grown from surface dielectric barrier discharge plasma-treated seeds. In a previous study, seeds were analyzed 6 days after plasma exposure and a plant stress and defense response was observed. Here, we performed a pathway analysis on differentially expressed genes and our results revealed again an increased expression of plant stress and defense, specifically glucosinolate pathway-related compounds. The main difference was that a different part of the plant defense response changed at 7 days, which was not previously observed at 6 days. With a 24-h delayed extraction time point, the glucosinolates were selectively broken down into nitriles among all of the glucosinolates catabolic products. Although information about nitriles is limited, it protects plants against biotic stresses and has variable toxicity depending on the interacting organism. More work needs to be performed to better understand which plasma seed treatment parameters affect plant defense; however, these preliminary findings suggest that an optimized plasma treatment could be used to elicit a plant defense response.