[PEPPo] positron capture magnet

[Andriy Ushakov]

Jay, thanks a lot for your calculation! 
It clearly shows how the addition of steel can significantly reduce the field in the target, and also that the 1.8 T peak field is too high for the water-cooled copper coil (unacceptable current density).

Regards,
Andriy

-----Original Message-----
From: PEPPo <peppo-bounces at jlab.org> On Behalf Of Jay Benesch via PEPPo
Sent: Thursday, October 12, 2023 10:11 AM
To: peppo at jlab.org
Subject: [PEPPo] positron capture magnet

I did a quick and dirty model of a water cooled copper capture solenoid
30 cm long with 30 cm IR and steel outside 20 cm IR.  In order to get
1.8 T peak I had to increase the current density to unacceptable levels with 10 cm radial extent so that is 24 cm in the attached.  Current density 1000 A/cm^2 in coil pack, that in the copper will be larger. 
Steel is 15 cm thick and still well into saturation.  There's a 1 cm gap between coil and steel.  Field at [0.0,-50] 1260 G, about a fifth of what Andriy showed.  Default "good magnet steel" BH curve used. Field will be a few percent lower if 6" cold rolled steel of easily available grade is used.