Positive sheath behaviour in low pressure Argon plasma

Schiesko, L.; Carrère, M.; Cartry, Gilles; Layet, J. M.

doi:10.1016/j.jnucmat.2007.01.137

Cited by 6 publications

(2 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For sample biases equal to -40 V and -20 V one observes a reduction of the number of collected negative ions and a diminution of the height of the main peak. This is related to the sheath voltage drop and to the angular emission of the negative ions (results not presented here 47 ). For a sample bias of -80 V or -130 V the negative ions see their trajectories modified by the large sheath voltage drop in comparison to their creation energy.…”

Section: Resultsmentioning

confidence: 81%

First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

Schiesko

Cartry

Hopf

et al. 2015

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

A study was conducted on the properties of molybdenum implanted with caesium as an approach to reduce the Cs consumption of negative hydrogen ion sources based on evaporated Cs. The depth profiles of the implanted Cs were simulated by SDTrimSP and experimentally determined by XPS depth profiling. In particular, one year after implantation, the depth profiles showed no signs of Cs diffusion into the molybdenum, suggesting long term stability of the implanted Cs atoms. The H − surface generation mechanisms on the implanted samples in hydrogen plasma were investigated and the stability of the H − yield during four hours low power hydrogen plasma discharges was demonstrated. An estimation of the work function reduction (-0.8 eV) by the Cs implantation was performed and a comparison of the relative negative ion yields between the implanted samples and highly oriented pyrolitic graphite (HOPG) showed that the Cs doped Mo negative ion yield was larger.

show abstract

Section: Resultsmentioning

confidence: 81%

First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

Schiesko

Cartry

Hopf

et al. 2015

Journal of Applied Physics

Self Cite

View full text Add to dashboard Cite

show abstract

“…In order to study negative-ion surface production in caesium-free plasmas in parallel to the development of Cybele, and in particular to study various layers of diamond materials, a dedicated experiment has been designed at PIIM laboratory [12,[38][39][40][41][42][43]. The aim is to evaluate and optimize alternative solutions to caesium prior to testing them in the Siphore negative-ion source.…”

Section: Negative Ion Production In Cybelementioning

confidence: 99%

R&D around a photoneutralizer-based NBI system (Siphore) in view of a DEMO Tokamak steady state fusion reactor

et al. 2015

View full text Add to dashboard Cite

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 (η > 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.

show abstract

Study of electron behavior in a pulsed ion sheath

Kar

Mukherjee

2008

Physics of Plasmas

View full text Add to dashboard Cite

In many plasma processing applications, like plasma immersion ion implantation (PIII), the substrate is immersed in low pressure plasma and is biased with negative voltage pulses. In typical PIII, the pulse duration is much larger than the ion response time, and hence the ion matrix sheath expands and ion implantation happens on the biased substrate. It is assumed that for pulse duration shorter than ion response times, the ions remain stationary and electrons are repelled by the negative bias. In the present investigation, the negative pulse duration is varied between ion and electron plasma response times; so as to study the electron behavior assuming ions are stationary. The results indicate that the electrons that are lost to the walls come from the ion matrix sheath and probably from the bulk plasma as well. The pulse duration, when it is less than the ion response time, plays a crucial role in determining the number of electrons lost to the walls.

show abstract

Positive sheath behaviour in low pressure Argon plasma

Cited by 6 publications

References 16 publications

First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

First experiments with Cs doped Mo as surface converter for negative hydrogen ion sources

R&D around a photoneutralizer-based NBI system (Siphore) in view of a DEMO Tokamak steady state fusion reactor

Study of electron behavior in a pulsed ion sheath

Contact Info

Product

Resources

About