draft:

Present: Dominique, James, Gunn, Yves Thurel, Edwin Rohrich, Frantisek Sanda

Dominique presentation:

• Latest iteration of the triplet magnet design presented
• Compared two options for the power converter: POLARIS and COMBO
• Dominique showed that with less number of turns and higher current (B-field ~turns*current), Polaris works
• With less current available from COMBO converters, number of turns and thus magnet/coil size needs to be increased. In terms of cost, magnet size and voltage drop, the POLARIS is better over COMBO. Indeed, with COMBO, trims need to be powered seperatly from the MAIN, with even two converters for the TRIMS, for adapting power to the proposed converter range. This results in  (1 MAIN + 2 for TRIMs) converters for each H or V BGI circcuit. In total, 12 power converters without counting live spare converters, would be necessary, where POLARIS would need only 4 in total (2 for Beam1 H&V BGI and 2 for Beam2 H&V BGI). Yves points out that the COMBO are relying on commercial brick power converters such as Delta Electronica (for example used for ELENA on surface). If converter fails, the swap take longer that the standard plug in modules used widely in LHC. The standby service is used to exchange power modules in less than 15 minutes, in case of fault thanks to an appropriate design, made on purpose. This would then require, in addition, some extra live spare converters, with total number of converters reaching 14 to 16 units, depending of the location of H&V converters, if they are installed all in the same area or not
• The laminated iron core originally proposed for the magnet (extra feature in case we wish to pulse the field) is no longer an option as the study shows iron saturation. WIth a triplet magnet, in theroy it will be transparent to the circulating beam (zero integrated field), we can leave the magnet ON all the time, the BGI runs with DC field. Thus, this is not an issue from intrument point of view.
• Next step is to now provide the residual field to the beams/operations to see if the design acceptable.
• Dominique is looking into field harmonics
• So in summary, it is POLARIS power converter that we go for !

Some additional notes:

• EN-CV is aware that we might need cooling water for power converter, this is now confirmed, they will be informed soon
• The cable with 400 mm2, 300m length between rack and instrument will result in about 13 V drop, should be counted in power converter consumption
• Magnet aperture = 156 mm
• Length = 2.2 m (old was 1.6 m) but can be reduced by optimisation in next iteration
• Check 3D model for integration with Jean Pierre Corso
• To be followed up in about 2 weeks time (involved other stake holders as well)