quench protection and the power supplies for the mice focusing and coupling magnets
DESCRIPTION
Quench Protection and the Power Supplies for the MICE Focusing and Coupling Magnets. Michael A Green Lawrence Berkley Laboratory 10 February 2005. Focusing and Coupling Magnet Quench Protection. - PowerPoint PPT PresentationTRANSCRIPT
1
Quench Protection and the Power Supplies for the MICE
Focusing and Coupling Magnets
Michael A Green
Lawrence Berkley Laboratory
10 February 2005
2
Focusing and Coupling Magnet Quench Protection
• The focusing and coupling magnets have a shorted secondary (the mandrel) to induce quench back in the coil for passive quench protection.
• Quench back will quench all magnets when more than one magnet is hooked up in series.
• Resistors and diodes across the coil will provide additional quench protection by shunting some current from the coil.
• The resistors and diodes limit the voltage within the coils during a magnet Quench.
3109876543210
0
50
100
150
200
250
300
Current 1Hot Spot T 1Current 2Hot Spot T 2
Time from the Start of the Quench (s)
Current in the Coil (A) and Hot Spot T (K)
Single Magnet
Three Magnets in Series
Unprotected Quenches of a Single Focusing Magnet and Three Focusing Magnets in the Flip Mode
L1 = 98.6 HE1 = 3.10 MJL3 = 295.2 HE3 = 9.30 MJ
4109876543210
0
50
100
150
200
250
300
Current 1Hot Spot T 1Current 3Hot Spot T 3
Time
Current in the Coil (A) and Hot Spot T (K)
Single Magnet Flip Mode
Single Magnet Non-flip Mode
Unprotected Quenches of a Single Focus Magnetin the Flip Mode and the Non-flip Mode
Lflip = 98.6 HEflip= 3.10 MJLnon-flip = 134.8 HEnon-flip = 4.65 MJ
The non-flip currentis the worst case.
5
Lab G Solenoid Power Supplyand Quench Protection
PSMandrelMagnetWarm ResistorWarm DiodePower Supply10 V, 300 A
Cryostat
6
Three MICE Focusing Coils in Serieswith Quench Protection
PSPower Supply10 V, 300 A
Total Inductance from 295 H to 410 H
7
111098765432100
50
100
150
200
250
300
Current 1Hot Spot T 1
Time after the Quench has Started (s)
Magnet Current (A) and Hot Spot Temperature (K)
An Unprotected Quenches of a Single Coupling Magnet
L1 = 563 HE = 12.8 MJ
8
Should the coupling coils be in series?
• One can argue this question either way, but the argument favor powering the coils separately.
• The inductance of a single coil is 563 H. It will take 3.4 hours to charge one coil at 10 V. The inductance of all other magnet circuits is less than the inductance of a single coupling coil.
• A single coupling coil produces force that are smaller than the maximum force with the coils hooked in series.
• A quench of the coupling magnet will probably quench the focusing magnets.
9
The MICE Coupling Coil Power Supplywith Quench Protection
PSPower Supply10 V, 300 A
Coupling MagnetMandrelCold DiodeCold ResistorInductance = 563 H
Note: The coil is shown split into two parts. The coil may besplit into three or four parts instead of two parts.
10
Detector Magnet Quenches
• The INFN magnet design is different from the focusing and coupling magnet design from a quench standpoint. Active quench protection is proposed. Quench back is not a factor in the quench.
• The current densities are lower so quenches are safe even without quench back from a mandrel.
• The detector should have separate 300 A leads on the match coils. The other three coils are in series with added 50 A power supplies across the end coils.
• Like detector coils can be put in series. The circuit inductances are less than 200 H.
11
Detector Magnet Power Supplies
PSPower Supply10 V, 300 A
PSPSPSPSPower Supply10 V, 50 A
Match 1 Match 2 End 1 Center End 2
12
Concluding Comments on Quenches
• The focusing and coupling magnets will have passive quench protection. The detector magnet will likely have an active quench protection system.
• The three focusing magnets should be in series.
• Each coupling magnet should have its own power supply to reduce the charge time.
• Like detector magnet coils can be put in series.
• A coupling coil quench will quench the rest of MICE. A focus coil quench will not quench a coupling coil.