Superconducting coils for damage studies

This page was created as source of information about small racetrack superconducting coils created for damage study foreseen in October 2022.

1. Measuring the gap size

The gap, where wire will be placed was designed to have a width of 4.9 mm (±0.1 mm). To check this, twelve different pieces were measured with micrometer (precision ±0.0001 mm).

It could be seen from the attached table that, the actual size of the gap is in fact more than 0.02 mm bigger.

2. Labeling the coils

To distinguish between coils, they were labeled with numbers between 0-29. The label is always on side where the winding is started. Following table specifies the coils.

Coil's number	Winding material	Tension	Additional information	Washers inserted	Current status	G10 holder on	Location
0	NbTi	8 kg	Used for test-winding with copper	Yes	Qualified	no	UniGe
1	NbTi	8 kg		Yes	Qualified	no	UniGe
2	NbTi	8 kg		Yes	Qualified	no	UniGe
3	NbTi	8 kg		Yes	Winded	no	UniGe
4	NbTi	8 kg	On terminal the insulation is broken	Yes	Winded	X	X
5	NbTi	8 kg		Yes	Winded	no	UniGe
6	NbTi	8 kg		Yes	Winded	no	UniGe
7	NbTi	8 kg		Yes	Winded	no	UniGe
8	NbTi	8 kg		Yes	Winded	no	UniGe
9	NbTi	8 kg		Yes	Winded	no	UniGe
10	NbTi	8 kg		Yes	Qualified	no	UniGe
11	NbTi	8 kg		Yes	Winded	no	UniGe
12	NbTi	8 kg		Yes	Winded	no	UniGe
13	Nb3Sn	5 kg		Yes	Unreacted	no	office
14	NbTi	8 kg		Yes	Winded	yes	UniGe
15	NbTi	8 kg		Yes	Winded	yes	UniGe
16	Nb3Sn	5 kg	Test soldering 1 - high temp tape added	Yes	Reacted	yes	Polymer lab
17	Nb3Sn	5 kg	1B soldering, A miss - high temp tape added	Yes	Qualified	yes	UniGe
18	Nb3Sn	5 kg	1B soldering, impossible to deatach from holder piece		Destroied	no	office
19	Nb3Sn	5 kg	1C soldering, careless handling, B;C miss - high temp tape added	Yes	Reacted	yes	Polymer lab
20	Nb3Sn	5 kg	1C soldering - high temp tape added	Yes	Reacted	yes	Polymer lab
21	Nb3Sn	5 kg	1C soldering - high temp tape added	Yes	Reacted	yes	Polymer lab
22	Nb3Sn	5 kg	1B soldering - high temp tape added	Yes	Reacted	yes	Polymer lab
23	Nb3Sn	5 kg	1B soldering, C miss - high temp tape added	Yes	Reacted	yes	Polymer lab
24	Nb3Sn	5 kg	1B soldering	Yes	Reacted	X	Polymer lab
25	Nb3Sn	5 kg		Yes	Unreacted	X	Daniel's office
26	Nb3Sn	5 kg	1C soldering - high temp tape added	Yes	Reacted	yes	Polymer lab
27	Nb3Sn	5 kg	1B soldering - high temp tape added	Yes	Reacted	yes	Polymer lab
28	Nb3Sn	5 kg	Test soldering 1, Dismount 1, Polish 1, drilled x 2 second time into copper	Yes	Impregnated	yes	UniGe
29	Nb3Sn	5 kg	1C soldering	Yes	Reacted	yes	Polymer lab

Test soldering1: coil was in oven @ 230C for 15 minutes, but apparently it was not enoght. After that the soldering paste was scratched away. After that another soldering was performed. Coil stayed in over for 15 minutes at 270C. For soldering a solder with Ag was used.

1B soldering:

1. Surface was cleaned with the alcohol
2. Small portion of soldering paste(Sn63Pb37) was applied just on strand
3. Coils were inserted into furnace for 10 minutes at 250C
4. It was not enough for 6 coils so another 20 minutes at 260C
5. Solder soaked in the groves, so small amount of solder was added where needed
6. Coils were taken out and it was cooling down
7. Coils were preheted again to 150C for 10 minutes
8. Voltage taps were soldered to the coil

1C soldering:

1. Surface was cleaned with the alcohol
2. Through holders, which hold SC wire one pair of voltage taps was put in
3. Small portion of soldering paste(Sn63Pb37) was applied just on strand
4. Coils were inserted into furnace for 20 minutes at 260C
5. All coils were taken out
6. Second pair of voltage taps was soldered on hot coils (once soldering paste deliquified)
7. On coils [19,20,29] during dismounting one voltage tap felt of (tap sticked to overlaying SC strand), so additional soldering of these taps was performed (preheat 10 minutes to 180C then solder)

Dismount 1: dismounting SS holder piece was done by putting a sharp knife in the interface between SS and Cu. By hammer two halfmoons was deatachted.

Polish 1: A small layer of resin after impregnation, which had to be taken out using a sharp knife and brushing mashine. The holes for screwing coil on VTI probe was full of epoxy, so had to be drilled out again.

17/08: new labes were created on last batch of 10 Nb3Sn coils. From #30 to #40. 38, 39 one tap lost => soldered on side. #40 all taps lost => one pair solderd on side.

(34 new is 29 old)

STATUS OF COILS ON 14TH OCTOBER:

Coil's number	Winding material	Tension	Additional information	Washers inserted	Current status	Location
0	NbTi	8 kg	Used for test-winding with copper	Yes	Qualified	Cryostat
1	NbTi	8 kg		Yes	Qualified	Cryostat
2	NbTi	8 kg		Yes	Qualified	C ryostat
3	NbTi	8 kg		Yes	Winded	office
4	NbTi	8 kg	On terminal the insulation is broken	Yes	Winded	office
5	NbTi	8 kg		Yes	Winded
6	NbTi	8 kg		Yes	Winded	Cryostat
7	NbTi	8 kg		Yes	Winded	Cryostat
8	NbTi	8 kg		Yes	Winded
9	NbTi	8 kg		Yes	Winded	office
10	NbTi	8 kg		Yes	Cryostat	Cryostat
11	NbTi	8 kg		Yes	Winded	office
12	NbTi	8 kg		Yes	Winded
14	NbTi	8 kg		Yes	Winded	Cryostat
15	NbTi	8 kg		Yes	Qualified	Cryostat

Coil's number	Winding material	Tension	Additional information	Washers inserted	Current status	G10 holder on	Location
13	Nb3Sn	5 kg		Yes	Unreacted	no	office
17	Nb3Sn	5 kg	1B soldering, A miss - high temp tape added, first qualified 15th July	Yes	Qualified	yes	office
18	Nb3Sn	5 kg	1B soldering, impossible to deatach from holder piece	Yes	Destroied	no	office
25	Nb3Sn	5 kg		Yes	Unreacted	X	Daniel's office ?
28	Nb3Sn	5 kg	Test soldering 1, Dismount 1, Polish 1, drilled x 2 second time into copper, second qualified on 25th July	Yes	Qualified	yes	UniGe

Coil's number	Winding material	Tension	Additional information	Washers inserted	Current status	Location
30	Nb3Sn	5 kg		Yes	Qualified	Cryostat
31	Nb3Sn	5 kg		Yes	Impregnated	office
32	Nb3Sn	5 kg		Yes	Qualified	C ryostat
33	Nb3Sn	5 kg		Yes	Qualified	Cryostat
34	Nb3Sn	5 kg		Yes	Qualified	Cryostat
35	Nb3Sn	5 kg		Yes	Qualified	Cryostat
36	Nb3Sn	5 kg		Yes	Qualified	Cryostat
37	Nb3Sn	5 kg		Yes	Qualified	Cryostat
38	Nb3Sn	5 kg		Yes	Qualified	Cryostat
39	Nb3Sn	5 kg		Yes	Impregnated	office
40	Nb3Sn	5 kg		Yes	Impregnated	office