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Mechanical 3D model transferred into CST . Mechanical 3D model transferred into CST .

Mechanical 3D model transferred into CST . - PowerPoint Presentation

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Uploaded On 2017-05-06

Mechanical 3D model transferred into CST . - PPT Presentation

2 nd Harmonic cavity meeting March 2 2017 Gennady Romanov On PA test set up one more time 2III2017 Gennady RomanovMechanical 3D model transferred into CST 2 CST tetrode model based on measurements built in PA test set up model ID: 545256

cst model mechanical gap model cst gap mechanical 2017 gennady transferred mhz romanov iii field surface cavity set electric

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Presentation Transcript

Slide1

Mechanical 3D model transferred into CST .

2nd Harmonic cavity meetingMarch 2, 2017

Gennady RomanovSlide2

On PA test set up one more time2/III-2017

Gennady Romanov|Mechanical 3D model transferred into CST2CST tetrode model based on measurements built in PA test set up model.Result of CST: f = 70.016 MHz, while the test data is 71.6 MHz All possible incorrectness in the PA model were fixed, the water load added. Result of CST: f = 70.6

MHz.

Anode-grid gap in the tetrode was increased by 0.508 mm (0.02”). Result of simulations: f = 71.648 MHz (≈ 1 MHz rise)

The anode-gap was increased by 0.508 mm in the 2

nd

harmonic cavity model. Results of FD simulations with uniform µ show weak impact of this change:

µ

Old

gapNew gapf high end, MHz1.3834104.05104.11f low end, MHz3.20875.86275.873

Abs electric field distribution in logarithmic scale

PA set up model

2

nd

harmonic cavity model

Frequency of the PA set up is defined mostly by the tetrode itself, because highest electric field is in the anode-grid gap. On the contrary in the 2nd harmonic assembly almost all electric energy is stored in the cavity. Therefore a sensitivity of frequency to the tetrode dimensions is very low (operating mode is assumed)Slide3

Mechanical solid model2/III-2017Gennady Romanov|Mechanical 3D model transferred into CST

3Kevin’s model from February 10, 2017

This position and orientation of the coordinates requires translation and rotation of the imported parts. Any part movement is a numerical operation with finite accuracy. To avoid possible errors during these manipulations, let’s define a common point of coordinate origin. Since this is an accelerator cavity, a natural choice is the accelerating gap.

Sharp edge and gap

Cooling tube goes through RF volume

A very complicated shape. How it is supposed to be built?Slide4

RF 3D model, first shot.2/III-2017

Gennady Romanov|Mechanical 3D model transferred into CST4EM, uniform µ = 1.3834 (corresponds to 575 A coil current), f = 101.4 MHz, ≈ 3 MHz down (from 104.11 MHz) because of this gap

Gap ≈ 0.01”

The parts of this color had to be made from scratch because:

1) Meshing of some CAD parts failed.

2) Meshing of the imported CST part failed either.

Tuning curve after the gap was closed. It is good, slightly reduced.

Surface currents on the gap edge

and on the end plate

Bolts, nuts and non-RF details removedSlide5

More about gaps2/III-2017Gennady Romanov|Mechanical 3D model transferred into CST

5

Surface electric field

outside RF volume

Temporary unrealistic solution

This gap may be closed, if we want a solid flangeSlide6

2/III-2017Gennady Romanov|Mechanical 3D model transferred into CST

6Fields and surface currents on slotsE_surf

General view of

E_surf

, field is

not normalized to V=100 kV

Surface current,

absolute

value

Narrow slots are not a concern. 100%≈130%Slide7

Garnet/ceramic at slots2/III-2017Gennady Romanov|Mechanical 3D model transferred into CST

7

Field enhancement on the wide slot

No noticeable field enhancement on the narrow slotSlide8

2/III-2017Gennady Romanov|Mechanical 3D model transferred into CST8

Garnet-ceramic connectionsAlumina

Garnet

E_surf

Copper

≈130%

Triple point is a singularity, so

the error of simulations may be very big. Therefore we can say for sure that surface field is enhanced there, but we don’t know how much.