SPS wire scanner prototype

Benoit Salvant and Carlo Zannini for the impedance team

With the help of Elena Chapochnikova, Jose Ferreira Somoza, Jose Varela and BI colleagues

SPSU meeting - 27/02/2013

Question• Bernd informed us that the wire scanner tank is likely

to be installed without the wire scanner. • Is that acceptable from longitudinal point of view?

Eigenmode simulation resultsMode frequency (GHz) Q Rs kOhm

1 0.568 6712 22 0.665 7681 33 0.666 7818 484 0.832 5706 365 0.864 7903 96 0.871 7737 127 0.875 8009 98 0.884 7883 239 0.998 11670 19

10 1.025 6541 1011 1.026 6527 412 1.061 8561 12313 1.127 8022 114 1.135 8017 015 1.143 6982 116 1.149 8939 017 1.153 8838 1118 1.160 7764 419 1.224 9911 6020 1.256 7481 0

Above TE11 cutoff of attached pipe (~1.09 GHz )

Is this acceptable from longitudinal point of view? Q should be lower in real lifeECR coming. We will anyway request bench measurements (probes in particular to assess the Q)

“Ugly” devices in the SPS? (from impedance point of view)

One example: near QF 41801

December 2013

CDD database

~2007From SPS OPsite

Some drawings missing and some not up to date

Impedance of “bare” bellow transition

Frequency

Shun

t im

peda

nce

in O

hm

Qs are of the order of 4000 to 8000

Impedance of transition with bellows

Frequency

Shun

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Qs are of the order of 500 to 3500

Shunt impedance could reach of the order of 100 kOhm (depends on actual length).

How to proceed?• The safest is to survey the machine in the tunnel half cell by half cell (drawings are not

up to date…). Can probably be done in two days.

• Survey points:– Potential issues for impedance– Where are the shielding of pumping ports missing (needs VAC colleagues as not obvious from

outside)– Where are damping resistors installed?– Other ideas?

• When?– Now is good as a lot of time and no radiation– But some parts of the machine are still not reinstalled

• Who?– Carlo, Jose, Fritz, Benoit ? needs

QF32210

Frequency (GHz)

Shun

t im

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100 kOhm

Also of the order of 100 kOhm (if Q is correct)