Update on the kicker impedance model and measurements of material properties

C. Zannini, G. Rumolo, V.G. Vaccaro

Thanks to: N. Biancacci, A. Danisi, H. Day, G. De Michele, E. Metral, B. Salvant

Penetration depth in ferrite

Overview

• Kicker impedance model

• Wire measurements

• Measurements of material properties

4

Simplified kicker model Courtesy T. Kroyer

5

Simulation models

C-magnet model

x

y

6

Comparing the two models

Using the C-magnet model in the transverse horizontal impedance a high peak at 40MHz appears. At low frequency the Tsutsui model is not able to estimate correctly the kicker impedance. The two models are in good agreement at high frequency (>400MHz).

Real horizontal quadrupolar impedance calculated at x=1 cm

7

Comparing the two modelsIm

peda

nce

[Ohm

]

Real vertical detuning impedance calculated at y=0.5cm

Real longitudinal impedance

We can see the peak also in the longitudinal and vertical impedance

C-magnet and Frame magnet

C-magnet model

x

y

Frame Magnet model

C-magnet and Frame magnet

Penetration depth in ferrite

Calculation of the impedance for the C-Magnet model

TSUNSCMagnet ZZZ

Where is the low frequency impedance in a C-Magnet kicker model calculated using the Sacherer Nassibian formalism and is the impedance calculated using the Tsutsui formalism. The Tsutsui impedance is calculated in H. Tsutsui. Transverse Coupling Impedance of a Simplified Ferrite Kicker Magnet Model. LHC Project Note 234, 2000. Instead we have to spend some word about the Sacherer Nassibian impedance.This impedance is defined as:

NSZTSUZ

gk

kx||NS

k||NS

ZLjZZblc|Z

acZ

Zbl)ax(Z

2

220

02

2

220

20

2

4

4

0

Where l is the length of the magnet, x0 the beam position, L the inductance of the magnet and Zg is the impedance seen by the kicker

12

Comparing with theoretical results

The simulations of the C-magnet model are in agreement with a theoretical prediction based on Sacherer-Nassibian and Tsutsui formalism

Horizontal driving impedance calculated at x=1cm: MKP

Frame Magnet modelHorizontal dipolar impedance

External circuits EK PSB

The green curve depends from the cable properties (propagation and attenuation constants)

14

MKP: horizontal transverse impedance

The segmentation seems to affect strongly the low frequency peak

Overview

• Kicker impedance model

• Wire measurements

• Measurements of material properties

16

Measurements of the coupling impedance using the coaxial wire method

The measured quantity is the transmission S21

proptruem QQQ111

For resonant structures:

cut-off frequency ≠0cut-off frequency =0

TEM Propagation losses

Measured Losses = True Losses + Propagation losses

17

seg

MKP: Comparing measured and simulated longitudinal impedance

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50760076

steelPEC

steelPEC

mrad

mradtrue

radPEC

msteel

QQQQ

QQQQQ

.QQ.QQ

Measurements of the coupling impedance using the coaxial wire method

radtruem QQQ111

cut-off frequency =5.74 GHz

Superfish 11463trueQ

Measurements of the coupling impedance using the coaxial wire method

Overview

• Kicker impedance model

• Wire measurements

• Measurements of material properties

21

Coaxial line method

We characterize the material at high frequency using the waveguide method

Electromagnetic characterization of materials

)'','(GS 21

),(G

),(

),(

Status of the measurements

We (me and G. De Michele) did measurements for some SiC in the ranges 10 MHz-2GHz and 8 - 40 GHz and for the ferrite 8C11 in the range 10MHz-10GHz

The elaboration of the results will take at least one month (simulation time of the measurement setups)

23

Ferrite Model

The ferrite has an hysteresis loop

The hysteresis effect in this measurements

μ

H

rB

m/A.H 80 TB r610

In this measurements for the coaxial ferrite sample we have:

11

hysteresis

truemeasured