sPHENIX discussion of the superconducting solenoid

["Than, Yatming (Roberto)" <ythan AT bnl.gov>]

Kin,

 

We need the beam bunch average diameter, is it 2.8 mm? So figure out impingement Area

How many bunches will hit the magnet before the rest is dumped in beam dump.

Convert this to Joules and divide by time to get unit of power:  Watts

Heat flux: Power/ Area  gives W/m^2

Basically we need power and duration of beam hit.

 

The beam will hit the inner cryostat wall first, which is the aluminum wall.

With the heat flux number we can calculate a surface temperature and penetration depth vs time.

 

Paul Orfin has an Ansys model where we can change material to aluminum and we can predict the peak temperature and see whether it melts.

[ 1-D ANSYS transient model for high heat flux, (1x10^8 W/m^2) onto a surface.]

The model [ mesh size and time interval] is set up to handle fast transient, of order 1-100 microseconds.

 

 

 

 

 

Roberto Than

Cryogenic Systems, Collider-Accelerator Department
Brookhaven National Laboratory
Building 1005S, MS 1005S, Room 212
Upton, NY 11973-5000
Telephone: (631) 344-7165
Cell 631-487-6842 
E-mail: ythan AT bnl.gov

 

From: sPHENIX-magnet-l [mailto:sphenix-magnet-l-bounces AT lists.bnl.gov] On Behalf Of Kin Yip
Sent: Tuesday, February 27, 2018 4:24 PM
To: Haggerty, John <haggerty AT bnl.gov>; Franz, Achim <afranz AT bnl.gov>; sphenix-magnet-l AT lists.bnl.gov
Subject: [Sphenix-magnet-l] energy deposited on the copper (superconducting wire)/aluminium-stabilizer

 

Hi John and Achim,

I used my usual MCNPX energy deposit simulation to do something quick (worst scenario). 

From the BaBar paper （like this one) :
https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Shared%20Documents/BaBar%20Documents/The%20BaBar%20Superconducting%20Coil;%20Design,%20Construction%20and%20Test.pdf

I made up a rectangle of 1.4 mm x 6.4 mm of copper (I didn't bother with NbTi) surrounded by the Al   8.4 mm x 20 mm.

Then, I hit proton directly on it (with some beam sigma if 0.28 cm  --- something that I used for the calculation in RHIC).   Quickly, I get the total energy deposit as such :

2.249 MeV/g per  proton  (hitting it) on the copper   and
1.18   MeV/g per proton                    on the Al stabilizer,

which are

3.6E-13 J/g per proton   and
1.9E-13 J/g per proton.


Our proton beam is said to have a max. of 2.5E13 (totaled from all 110 bunches).   I'm not sure who can make the beam turn 90 deg. and hit the Magnet.   But let's say that it's possible
that all the beams were dumped in one spot of the Magnet coil, the total energies are

~9.0 J/g  (Cu)  and  4.7 J/g (Al-stabilizer) .

From the Enthalpy curve (eg. Fig 3 on p.5) :
https://collab.external.bnl.gov/sites/sPHENIX-Magnet/Shared%20Documents/Miscellaneous%20(General%20Knowledge)/Material%20Properties%20at%20Low%20Temperature.pdf

or some others that Bob Lambiase showed me,

the temperature rise would be < 100K.    So, it'd probably quench the magnet but it won't burn a hole.  

If George or somebody asked this kind of question again in future review, I would answer with the above.   Please let me know if you somebody find something critically wrong.

Kin