Kiel Nano, Surface and Interface Science (KiNSIS)

Tiberiu Minea (Paris-Sud): Modeling of vacuum breakdown

13.06.2017 ab 17:15

Hans-Geiger-Hörsaal ( Leibnizstr. 13, Raum 52)

Abstract


Tiberiu Minea (Paris-Sud): Modeling of vacuum breakdown. Thermo-field, dynamics of microparticles and laser assisted electron emission

Vacuum is often used as an isolator in numerous applications, such as X-ray tubes, particle accelerators, high voltage pass-through, etc. However, their performance is limited by the risk of unpredictable breakdown events between electrodes. Moreover, the breakdown usually leads to the formation of arc discharges, which can seriously damage the system.

Since 2010 the LPGP develops a research program “High Voltage holding In Vacuum”, in collaboration with CEA and CentraleSupelec which aims to give a better description of the origin of the vacuum breakdown.

Three numerical models have been developed to tackles three particular aspects of the problem.

(i) The model OVIP (Orsay Vacuum Insulation Percolation) deals with the thermos-field electron emission from a surface microprotrusion and the results are in good agreement with the experimental results for breakdown. The operation with fast pulses allows to enhance the field emission avoiding the breakdown.

(ii) The model OFEN (Orsay Field Emission Nanoparticles) describes the micro-particles (MP) transport in the inter-electrodes gap, in vacuum) and the interactions (heating and modification of the MP charge) between electrons and the MP. It is an extension of the Cranberg’s theory of clumps when the MP is exposed to an intense field ~1-5 MV/m and it is simultaneous bombarded by electrons released from the cathode micro-tips. The results clearly show four different regimes of MP trajectories obtained for different emission currents, MP sizes and inter-electrode distances and the effect of the MP crash of on the cathode, helping to understand the vacuum conditioning.

(iii) The last model OFELIE (Orsay Field Emission and Light Emission) analysis the electron emission induced by picosecond laser from solid surfaces placed under an intense electric field. The results show an important difference between the electrons temperature (5500 K) and the phonons temperature (850 K). In these conditions, the Fermi-Dirac distribution depends of the electron temperature, while the thermo-field emission becomes effective for temperatures well below the fusion of the metal.

In conclusion, the modeling of the related phenomena between solid and vacuum depends on the way the energy is transferred to the electrons and it helps to distinguish between different scenarios and to design performant systems.

Diesen Termin meinem iCal-Kalender hinzufügen

zurück

Pressemitteilungen

Medien

Veranstaltungen

Kalender

« Mai 2018 »
Mo Di Mi Do Fr Sa So
30 1 2 3 4
  • 14:00: Diels-Planck-Lecture 2018 an Professor Dr. Maki Kawai, Okazaki
  • Klicken Sie, um Details zu allen 1 Terminen zu sehen.
5 6
7 8
  • 16:15: Plasma Potential Distribution and Electron Heating in Sputtering Magnetrons (Prof. Dr. A. Anders, Leibniz Institute of Surface Engineering)
  • Klicken Sie, um Details zu allen 1 Terminen zu sehen.
9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28
  • 17:15: Acoustic wave lab-on-chip is now flexible, bendable and potentially wearable! (Prof. Richard Fu, Newcastle)
  • Klicken Sie, um Details zu allen 1 Terminen zu sehen.
29
  • 16:15: Wires, trusses and pillars produced by assembly of plasma generated nanopartices (Prof. Dr. Ulf Helmersson, Linköping University, Schweden)
  • 16:15: Wires, trusses and pillars produced by assembly of plasma generated nanopartices (Prof. Dr. Ulf Helmersson, Linköping University, Schweden)
  • Klicken Sie, um Details zu allen 2 Terminen zu sehen.
30
  • ganztägig: Nanotechnology and Innovation in Baltic Sea Region 2018 (NIBS)
  • Klicken Sie, um Details zu allen 1 Terminen zu sehen.
31
  • ganztägig: Nanotechnology and Innovation in Baltic Sea Region 2018 (NIBS)
  • 17:00: Low-energy electron transport in water: Aerosol droplets, molecular clusters, and liquid bulk, Prof. Ruth Signorell (ETH Zürich)
  • Klicken Sie, um Details zu allen 2 Terminen zu sehen.
1
  • ganztägig: Nanotechnology and Innovation in Baltic Sea Region 2018 (NIBS)
  • Klicken Sie, um Details zu allen 1 Terminen zu sehen.
2 3