scholarly journals Studies of enhanced field emission relevant to high field superconducting radio frequency devices

2021 ◽  
pp. 7-7
Author(s):  
Marija Radmilovic-Radjenovic ◽  
Zeljka Nikitovic ◽  
Ranislav Radjenovic
Keyword(s):  
Electric Field ◽  
Radio Frequency ◽  
Field Emission ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Field Enhancement Factor ◽  
Accurate Estimation ◽  
Cavity Surface ◽  
Planar Surfaces ◽  
Superconducting Radio Frequency

Surface roughness represents the measure of the irregularities on the surface contributing to the local field enhancement. The traditional Fowler-Nordheim equation established for perfectly planar surfaces is not suitable for describing emission from rough surfaces. Instead, it is more appropriate to use the equation that accounts for the field enhancement factor describing the effect of the surface morphology. In superconducting radio frequency cavities field emission may occur in the irises and the tips on the cavity surface may act as an emitter leading to the high electric field. For this study, calculations for hemispherical, cylindrical, and conical tips have been performed by using a multiphysics software package COMSOL. The focus was put on the dependence of the field enhancement factor on the shape and the radius of the protrusions. The electric field strength and the current density increase with increasing the root mean square average of the profile heights due to field enhancement at the cavity irises. The lowest value of the electric field has been achieved for the hemisphere. The calculated values for the field enhancement factors are consistent with the data from the literature, in which case the protrusion may represent a small local bump on the surface of a superconducting cavity. Based on the fit of the results, presented here, the relation between the enhancement factor and the radius has been suggested. The accurate estimation of the field emission may play a crucial role in the design of accelerators and other technological applications with requirements of very high precision.

scholarly journals The effect of the enhanced field emission on the characteristics of the superconducting radio frequency cavities

2018 ◽  
Vol 33 (4) ◽  
pp. 341-346
Author(s):  
Marija Radmilovic-Radjenovic ◽  
Petar Belicev ◽  
Branislav Radjenovic
Keyword(s):  
Radio Frequency ◽  
Field Emission ◽  
Enhancement Factor ◽  
Effective Area ◽  
Cavity Surface ◽  
Superconducting Radio Frequency ◽  
Superconducting Cavities ◽  
Electron Field ◽  
Modal Field ◽  
And Control

Electron field emission limiting the accelerating gradient in superconducting cavities remains the dominant setback in cavity production. The need to understand and control the field emission has become increasingly important because of the prospect of using high-gradient structures in linear colliders. Since building an accelerator structure is a complicated and costly process, elimination of unnecessary steps has priority. In this paper an analysis of the influence of the enhanced field emission in superconducting radio frequency cavity together with modal field calculations by using COMSOL finite elements package has been presented. The obtained results reveal that the electric field required for the field emission is generated in the cavity irises. The imperfection of the cavity surface leading to very high fields is modelled by a simple cone. The estimated value of the enhancement factor for the cone tip of around 4 is in a good agreement with the data found in the literature. In addition, from the slopes and the intercepts of the Fowler-Nordheim plots, a dependence of the enhancement factor and the effective area on the work function has been estimated.

Effect of distribution of field enhancement factor on field emission from cathode with a large number of emission sites

2005 ◽  
Vol 484 (1-2) ◽  
pp. 379-381 ◽  
Author(s):  
Guang Yuan ◽  
Hang Song ◽  
Yixin Jin ◽  
Hidenori Mimura ◽  
Kuniyoshi Yokoo
Keyword(s):  
Field Emission ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Field Enhancement Factor

scholarly journals Distribution of earth atmospheric electric field in the vicinity of the vehicles for transport petroleum derivates

2006 ◽  
Vol 19 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Alenka Milovanovic
Keyword(s):  
Electric Field ◽  
Human Body ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Field Enhancement Factor ◽  
Atmospheric Electric Field ◽  
Electric Field Enhancement ◽  
Petrol Station ◽  
Electrode Method ◽  
Petrol Pump

In this paper using Equivalent Electrode Method (EEM) Atmospheric Electric Field (AEF) distribution in the vicinity of the cargo vehicle is approximately numerically determined, when the vehicles are situated on petrol station near by petrol pump and people. The petrol pump is always grounded, but human body and vehicle are treated as grounded or 'floating' electrodes. Several results of electric field enhancement factor for the vehicle including maps of equienergetic curves are presented.

scholarly journals Field enhancement factor and field emission from a hemi-ellipsoidal metallic needle

2009 ◽  
Vol 109 (4) ◽  
pp. 373-378 ◽  
Author(s):  
Evgeny G. Pogorelov ◽  
Alexander I. Zhbanov ◽  
Yia-Chung Chang
Keyword(s):  
Field Emission ◽  
Enhancement Factor ◽  
Field Enhancement ◽  
Field Enhancement Factor

Template synthesis of metal tungsten nanowire bundles with high field electron emission performance

RSC Advances ◽  
2016 ◽  
Vol 6 (67) ◽  
pp. 62668-62674 ◽  
Author(s):  
Yong Liu ◽  
Kun Lan ◽  
Mahir H. Es-Saheb ◽  
Ahmed A. Elzatahry ◽  
Dongyuan Zhao
Keyword(s):  
Field Emission ◽  
Template Synthesis ◽  
Electron Emission ◽  
Enhancement Factor ◽  
High Field ◽  
Field Enhancement ◽  
Field Electron Emission ◽  
Field Enhancement Factor ◽  
Emission Performance ◽  
Turn On

A H2 reduction-assisted hard-templating approach is demonstrated to synthesize metallic W nanowire bundles. The W nanowire bundles show a low turn-on field of 4.1 V μm−1, a high field enhancement factor up to 3563 and good field emission stability.

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