sps wire scanner impedance and wire heating studies

SPS WIRE SCANNER IMPEDANCE AND WIRE HEATING STUDIES

Impedance Meeting19/05/2014

E. Piselli, O. E. Berrig, F. Caspers, B. Dehning, J. Emery, M. Hamani,J. Kuczerowski, B. Salvant, R. Sautier, R. Veness, C. Vuitton, C. Zannini

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Motivations

CERN-SPS WIRE SCANNER IMPEDANCE AND WIRE HEATING STUDIESE. Piselli, O. E. Berrig, F. Caspers, B. Dehning, J. Emery, M. Hamani,

J. Kuczerowski, B. Salvant, R. Sautier, R. Veness, C. Vuitton, C. ZanniniCERN, Geneva, Switzerland

 This article describes a study performed on one of the SPS vertical rotational wire scanners in order to investigate the breakage of the wire, which occurred on several occasions during the last year of operation. The thermionic emission current of the wire was measured to evaluate temperature changes, and was observed to rise significantly as the wire approached the ultimate LHC beam in the SPS, indicating the possibility of strong coupling between the beam’s electromagnetic field and the wire. Different laboratory measurements, complemented by CST Microwave Studio simulations, have therefore been performed to try and understand the RF modes responsible for this heating. These results are presented here, along with the subsequent modifications adopted on all of the operational SPS wire scanners.

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SPS BWS416

beamV BWS H BWS

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SPS Vertical BWS416

Vertical insertionplate

W wire(Fritz)

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Measurements

Vertical BWS

Horizontal BWSProbe

HybridΣ Δ

0-2GHz

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

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Measurements

Sum 15cm out

Diff15cm out

200-400MHz

HOME IN

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Measurements

Sum 15cm out

Diff15cm out

600-800MHz

INHOME

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Measurements

Sum 25cm out

Diff25cm out

200-400MHz

HOME IN

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Measurements

Sum 25cm out

Diff25cm out

600-800MHz

HOME IN

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Simulations

Diff25cm out

Sum25cm out

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Conclusions

• The tungsten wire insertion seems to improve an average of 7dB

• The insertion plates have a stronger effect at high frequencies

• Simulations seems to follow quite the measurements

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Emiliano

Grazie