6th International Workshop on Mechanisms of Vacuum Arcs (MeVArc 2017)

Session

Experiments and Diagnostics

ED

Mar 22, 2017, 8:30 AM

Other Institutes

33. STUDIES OF HIGH-POWER MICROWAVE STRUCTURES THAT EMPLOY BIMODAL CAVITIES

Jay L Hirshfield (Yale University & Omega-P, Inc.)

3/22/17, 8:30 AM

Experiments and Diagnostics

oral

Y. Jiang, (1) S.V. Shchelkunov, (1,2) X.Chang, (1) and J.L. Hirshfield, (1,2)

1 Beam Physics Laboratory, Yale University, New Haven, CT 06511 (USA)
2 Omega-P R&D, Inc. New Haven, CT 06511 (USA)

ABSTRACT

Theory and simulations predict that metallic microwave accelerating structures, including RF guns, should operate at high acceleration gradients with reduced breakdown rates and/or with...

35. RF breakdown study on choke-mode damped accelerating structures

Jiaru Shi (Tsinghua University)

3/22/17, 9:15 AM

Experiments and Diagnostics

oral

X-band high gradient accelerating structures has been studied in Tsinghua University, especially the choke-mode damped structure. Several single-cell standing-wave structures have been built for high power test. One choke-mode structure achieved a max gradient of 75 MV/m and the choke breakdown limited further increasing of the gradient. Postmortem inner surface inspection of the choke-mode...

14. Arcing on fuzzy nanostructures

Shin Kajita

3/22/17, 10:00 AM

Experiments and Diagnostics

oral

Helium ion bombardment, which can occur on plasma facing walls in nuclear fusion devices, forms metallic fuzzy nanostructures on the surface [1]. Interestingly the nanostructure growth accompanied by helium bubble formation occurs on various metals, such as tungsten, molybdenum, tantalum, iron, nickel, and rhenium. In this study, we conducted (unipolar) arc experiments using the nanostructured...

31. Influence of Cathode Melted Layer on Vacuum Insulation

Zhiyuan Liu (Xi'an Jiaotong University)

3/22/17, 11:00 AM

Experiments and Diagnostics

oral

The objective of this paper is to determine influence of depth of cathode melted layer on vacuum insulation. A 12kV vacuum interrupter with a pair of rod-plane electrode was designed. A DC current source is applied on the test vacuum interrupter, in which the rod electrode is chosen as anode. A drawn vacuum arc is used to generate different depth of melted layer on the rod electrode in an...

17. The spatial evolution of species during vacuum breakdown

Zhenxing Wang (Xi'an Jiaotong University)

3/22/17, 11:30 AM

Experiments and Diagnostics

oral

The initial stage of vacuum breakdown is still lack of direct experimental evidence because it is difficult to observe and measure. The objective of this study is to observe the light emission in the initial stage by optical diagnosis.We adopted a ICCD camera to catch a series of images in a breakdown and two optical filters to distinguish the light from copper atom (Cu I ) or singly charged...

5. Gas breakdown investigation and mitigation in complex geometries

Dr Fabio Avino (École polytechnique fédérale de Lausanne - EPFL, Switzerland)

3/22/17, 12:00 PM

Applications and Background

oral

Increasing satellite bus voltages from 28-100 V to 300-600 V is presently under investigation [1]. High voltages will be required to power new generations of ion and Hall effect thrusters [2], with higher power efficiencies, lower power system costs and substantial mass savings. At the same time, increasing bus voltage could lead to a higher risk of electrical breakdown for several satellite...

11. Dislocation patterns in Cu-OFE by EBSD and Breakdown activity

Enrique Rodriguez Castro (University of Vigo (ES))

3/22/17, 2:00 PM

oral

In the frame of the CLIC (Compact Lineal Collider) study for the development of a two-beam accelerating technology for a future TeV–scale e+e- linear collider, electrical breakdown (BD) phenomena are deeply studied. BDs are caused by the interaction of the oxygen free electronic copper (Cu-OFE) with vacuum arcs at high gradient operation. BD phenomena lead to isolated or clusters of craters on...

25. Observations of pre- and post-breakdown structures on OFHC Cu surfaces

Mrs Ayelet Yashar (The Hebrew University of Jerusalem), Dr Inna Popov (The Hebrew University of Jerusalem)

3/22/17, 2:30 PM

Experiments and Diagnostics

oral

Numerous devices featuring diverse applications contain metal that is exposed to high electric fields and operate under a vacuum. At high electric fields, an occurrence of plasma formation inside the vacuum can lead to breakdown [BD] and failure of the device. Despite the fact that the detailed mechanisms controlling BD have been the subject of extensive study for the past several decades,...