Entire plasmas can be restructured when electrons are emitted from the boundaries

Campanell, Michael

doi:10.1063/1.4918339

Cited by 23 publications

(22 citation statements)

References 37 publications

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“…Methods, such as the inflection point method [210], have been developed to improve the accuracy of emissive probe measurements associated with this effect [211]. It has also been demonstrated experimentally [212] and studied using PIC simulations [213,214,215] that plasmas bounded by strongly emitting boundaries can be made to have a negative plasma potential with respect to the conducting boundaries. Here, double sheaths similar to that depicted in figure 4 were observed [212], but where the bulk plasma potential was below the electrode potential.…”

Section: Electron Emitting Surfacesmentioning

confidence: 99%

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Baalrud

Scheiner

Yee

et al. 2020

Plasma Sources Sci. Technol.

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Biased electrodes are common components of plasma sources and diagnostics. The plasma-electrode interaction is mediated by an intervening sheath structure that influences properties of the electrons and ions contacting the electrode surface, as well as how the electrode influences properties of the bulk plasma. A rich variety of sheath structures have been observed, including ion sheaths, electron sheaths, double sheaths, double layers, anode glow, and fireballs. These represent complex self-organized responses of the plasma that depend not only on the local influence of the electrode, but also on the global properties of the plasma and the other boundaries that it is in contact with. This review summarizes recent advances in understanding the conditions under which each type of sheath forms, what the basic stability criteria and steady-state properties of each are, and the ways in which each can influence plasma-boundary interactions and bulk plasma properties. These results may be of interest to a number of application areas where biased electrodes are used, including diagnostics, plasma modification of materials, plasma sources, electric propulsion, and the interaction of plasmas with objects in space.

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Section: Electron Emitting Surfacesmentioning

confidence: 99%

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Baalrud

Scheiner

Yee

et al. 2020

Plasma Sources Sci. Technol.

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“…In the "inverse regime" the sheath potential is positive, opposite in sign from the SCL. An inverted presheath has a force balance unrelated to Bohm presheaths [14]. The particle and energy fluxes in the inverse regime are much different from the SCL regime.…”

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confidence: 99%

Strongly Emitting Surfaces Unable to Float below Plasma Potential

2016

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“…1.1, which reduces the electron flux to the electrode so that the electron and ion currents lost can be balanced. This feature is a type of virtual cathode that can occur near plasma boundaries, although they are also present in situations where charge particles are emitted from the electrode [28]. The dependence of sheath structure on the ratio A E /A W has been observed in experiments [16,17] and particle-in-cell simulations [35].…”

Section: )mentioning

confidence: 88%

“…In both of these cases there was an observed di↵erence between the behavior of positively and negatively biased electrodes suggesting a di↵erence in the processes responsible for the electrode behavior. A theory of positively biased electrodes may also have applications to the high potential phase of the RF cycle [26] and near strongly emitting surfaces [27,28].…”

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confidence: 99%

Theory and simulation of electron sheaths and anode spots in low pressure laboratory plasmas

Scheiner¹

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ACKNOWLEDGEMENTSThis work benefited from the input, help, and feedback of several people. This research was done in collaboration with Scott Baalrud, Matt Hopkins, Ed Barnat, and Ben Yee. Scott has been a great advisor. He took the time to check the details of nearly all of my work, pointing out countless mistakes and making several suggestions along the way. This not only included research results, but also seminar and conference talks, papers, and abstracts. I'm grateful for the encouragement and feedback when exploring new ideas and the pressure to stay focused and not stray too far from the current task at hand. Matt Hopkins was my mentor during the year I spent at Sandia National Lab under the O ce of Science Graduate Student Research program. Matt sponsored my application to the SCGSR program. Without his e↵ort, simulation of plasmas would not have played as great of a role as it has. I consider my experience simulating plasma experiments at Sandia to have been the most transformative of my graduate career. This will be invaluable as I move on to study new problems. At Sandia, I benefited from weekly discussions with Ed, Matt, and Ben on di↵erent issues relating to their various research topics in low temperature plasmas. Being in an environmentsurrounded by other plasma physicists working on related problems helped me distinguish which problems were interesting and useful to other people working in the field. The discussion of experimental results with Ben and Ed helped me to develop an understanding of these topics and to understand what things are and are not di cult to measure in the lab. Eventually I learned to stop asking for the impossible, although Ed may disagree. I enjoyed the hours spent talking plasma physics (or other less useful topics) around Andy Fierro's giant candy bowl with Ben, Ricky Tang, and Jim Franek. Also, the near daily breakfast burrito trips that Andy and I took made the food further east seem bland and nearly unbearable.At Iowa, there were several people who made day to day life more interesting. The two most notable are Ryan Hood and Nathaniel Sha↵er. Ryan always stopped by to talk about the latest thing that happened in the lab, or the latest Regular Car Review, and was always kind enough to show me his experiment and latest measurements. I've known Nathaniel since 2009 and am glad to have had a friend with whom I could bounce ideas o↵ of for so many years. I have no doubt that our various 'idiot checks' have vastly reduced the number of mistakes that could have been in these chapters. I have no doubt that both Nathaniel and Ryan will be great plasma physicists.Finally, I want to thank my family and friends for their support, especially my fiancè Mary ii for understanding the many late nights and stress filled days. I could not have done this without her support and love. ABSTRACTElectrodes in low pressure laboratory plasmas have a multitude of possible sheath structures when biased at a large positive potential. When the size of the electrode is small enough the electrode bia...

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Entire plasmas can be restructured when electrons are emitted from the boundaries

Cited by 23 publications

References 37 publications

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Interaction of biased electrodes and plasmas: sheaths, double layers, and fireballs

Strongly Emitting Surfaces Unable to Float below Plasma Potential

Theory and simulation of electron sheaths and anode spots in low pressure laboratory plasmas

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