From: Elias Metral

Sent: Wednesday, March 14, 2012 12:25 PM

To: Ralph Wolfgang Assmann; Stefano Redaelli; Oliver Aberle; Roberto Losito; Vincent Baglin

Cc: Fritz Caspers; Alexej Grudiev; Hugo Alistair Day; Benoit Salvant

Subject: RE: Recommendations from impedance team on TCTP

Dear colleagues,

Please find in this email the confirmation of the recommendations sent previously (below) for the new TCTP collimators without transverse RF fingers (but with the longitudinal RF fingers and additional ferrite on top of the jaws), with the requested additional information concerning the heat load and the ferrite:

1) It is proposed to use the ferrite TT2-111R which has a much higher Curie temperature (~ 400 deg C) than for instance 4S60 (~ 100 deg C).

2) The impedance team would like to make measurements on a sample of this ferrite to check the magnetic properties.

3) With the current knowledge, the maximum heat load to the ferrite is believed to be of the order of several Watts.

4) The vacuum team (we add Vincent in the email for this reason) should check the outgassing rate vs. temperature and give the maximum allowed temperature. What do you think Vincent?

Please tell us if you need more information from our side.

Best regards, Alexej, Benoit, Fritz, Hugo and Elias (for the impedance team).

---

From: Benoit Salvant
Sent: 18 October 2011 14:30
To: LHC-TertiartyCollimatorswithEmbeddedBPMs (Tertiarty Collimators with Embedded BPMs Design Meeting)
Cc: Fritz Caspers; Ralph Wolfgang Assmann; Elias Metral; Alexej Grudiev; Carlo Zannini; Hugo Alistair Day; Alessandro Dallocchio
Subject: Recommendations from impedance team on TCTP

Dear all,

Following an impedance meeting yesterday with Ralph (see the attached slides presented at this occasion), the following recommendation is issued:

-------------------------------------------------------------------

Acknowledging that

(1) the large jaw gaps used for nominal 7 TeV conditions for the 8 TCTP and the TCSG in 6, which lead to a small transverse impedance increase for the LHC at the 1 to 2% level) that is expected to be manageable by octupoles,

(2) the new simulation results which show an expected beneficial effect of ferrite in damping not only the transverse mode generated by the open plate gap but also the longitudinal modes,

the impedance team and ABP advise to use the design with ferrite on top of the jaw with the conditions that

(1) both a ferrite material sample and a collimator assembly prototype are qualified by the impedance team with RF measurements,

(2) the half gap between the jaws of the TCTP and TCSG6 is not significantly reduced below resp. 5mm and 3.6 mm during nominal operation at 7 TeV and for nominal beam intensities (relying on the increase of the beta_max in the triplets during further squeeze).

The impedance team should specify the type of ferrite, the maximum heat load to the ferrite and the maximum operating temperature.

Finally it must be clear that this design should be further optimized for other new collimator designs with small collimation gaps (e.g. phase 2 collimators for IR3 and IR7). 

------------------------------------------------------------------

Please do not hesitate to contact me if you have further questions or comments.

With best regards

Benoit Salvant