cavity Zenghai Li & Lixin Ge Z. Li & L. Ge MAP Weekly - - PowerPoint PPT Presentation

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cavity Zenghai Li & Lixin Ge Z. Li & L. Ge MAP Weekly - - PowerPoint PPT Presentation

Aug 15, 2023 209 likes •385 views

Design of the new 805 pillbox cavity Zenghai Li & Lixin Ge Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012 Outline Cavity Design Multipacting comparison DC comparison Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

slide-1
SLIDE 1

Design of the new 805 pillbox cavity

Zenghai Li & Lixin Ge

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012
slide-2
SLIDE 2

Outline

  • Cavity Design
  • Multipacting comparison
  • DC comparison
  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012
slide-3
SLIDE 3

New Design With Low Surface Field

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

slot slot 2 end bp anose E B E B Original New low field design

  • Large rounding and elliptical profile
  • Factor 0.55 reduction in surface E field
  • Factor 0.63 reduction in surface H field

Q0=16060 Model# slot height slot rounding slot rounding 2 anose Emax slot Emax slot2 Emax anose Emax end bp Emax

  • ther

surface Hmax slot angle Qext Original 15.2/6.4 3.175 11.4 69.81 44.95 32.88 46.22 0.304 53 12899 New (4c) 13.5/4.4 9.5 3.5 22 38.15 33.10 34.70 33.33 32.86 0.197 47.3 14645

slide-4
SLIDE 4

Multipacting Simulation Using Track3P

  • Part of ACE3P (Omega3P, S3P, T3P, Track3P, etc)
  • 3D parallel particle tracking in high-order finite-

element mesh

  • Analyze resonant trajectories
  • Use impact energy and SEY to estimate MP

strength

  • Copper SEY peak around 800eV impact energy
  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012
slide-5
SLIDE 5

Multipacting Analysis

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Original Design New Design

  • Field level scan: 0.1MV/m – 30MV/m,

interval 0.1MV/m

  • Initial Particles distributed on all

exterior surface

  • Each field level ran 50 RF cycles

Window Disk rounding Coupling iris Other

slide-6
SLIDE 6

Multipacting on Window Surface

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Original Design New Design

slide-7
SLIDE 7

Multipacting on Disk Rounding

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Original Design New Design

slide-8
SLIDE 8

Multipacting on Coupling Iris

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Original Design New Design

Larger coupling iris rounding area in new design

slide-9
SLIDE 9

Multipacting other exterior surface

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Original Design New Design

slide-10
SLIDE 10

Field Emission Simulation

To Study Relative Quantities

  • Gradient: 25 MV/m
  • Beta = 150 (normally use 50 for copper)
  • Emitted all the surface based on Folwer

Noheim field emission

  • No secondary
  • To compare, (as function of rf phase)

– Impact Energy – Current – Distribution

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012
  • riginal

new

slide-11
SLIDE 11

DC Analysis By Region

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Window Other surfaces Disk rounding Coupling iris

slide-12
SLIDE 12

Original Design New Design

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

(relative rf phase between original and new is arbitrary)

Energy v.s. Phase Current v.s. Phase

Window Disk rounding Coupling iris Other surfaces

slide-13
SLIDE 13

DC on Window

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Red: Original Design Green: New Design (relative phase between two designs is arbitrary)

  • Similar impact energy
  • Similar DC current on the window surface

(same E field)

slide-14
SLIDE 14

DC on Disk Rounding

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Red: Original Design Green: New Design (relative phase between two designs is arbitrary)

  • Similar impact energy
  • Higher current in the original design due to

higher field enhancement on the disk rounding surface

slide-15
SLIDE 15

DC on Coupling Slot

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Red: Original Design Green: New Design (relative phase between two designs is arbitrary)

  • Similar impact energy
  • Higher current in the original design due to

higher field enhancement on the coupling slot surface

slide-16
SLIDE 16

DC on Other Surfaces

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012

Red: Original Design Green: New Design (relative phase between two designs is arbitrary)

  • Similar impact energy
  • Higher current in the original design due to

higher field enhancement (around the coupling slot and disk rounding regions)

slide-17
SLIDE 17

Summery

  • New Design has incorporated large rounding

around the coupling iris and elliptical profile around the disk area

– Factor 0.55 reduction in surface E field – Factor 0.63 reduction in surface H field

  • Multipacting compared between original and

new design, no improvement indicated. (MP can normally be processed through)

  • Relative DC reduced significantly at a given

gradient

  • Would like to compare with measurement data

to help understand HP processing

  • Z. Li & L. Ge MAP Weekly Meeting, Jan 20, 2012