Hi-pot results summary

Speaker - Lab

MQXFA Electrical requirements and He BD

voltages

2

Component V_test

@ warm

V_test

@ 1.9 K

V_test

@ warm

after He

Coil-Ground 3680 V 1840 V 368 V

Coil-Heater 3680 V 2300 V 460 V

Failure 10 K 75 K 150 K 300 K

He Breakdown

Voltage (0.2 mm)

300 V 350 V 270 K 200 V

(2018-04-23)

MQXFA Electrical Design Criteria: EDMS 1963398 v4/ DocDb

Design 10 K 75 K 150 K 300 K

Polyimide BD

Voltage (50 mm)

10000 V 7000 K

He BD (4 mm) 11000 V 2500 V 1500 V 900 V

MQXF coils (Test after fabrication)

3

▪ Coil to quench heater requirements: 3680 V

(since ~04/18)

55 coils have been tested after fabrication

#

coil

2000

V

2500

V

3000

V

3200

V

3680

V

3700

V

5000

V

Short

model

29 1 23 3 1 1

MQXFA 18 2 11 5

MQXFB 8 4 4

No issues but test voltages changed over time

4

MQXFS3 @CERN after cold test

▪ Coil 105, 106, 107

▪ 5 thermal cycles

▪ 1 full disassembly

▪ ~100 quenches

105 106 107 8

OLL 3900 V * 5000 V 5000 V 5000 V

OLH 2300 V* 3600 V 5000 V 5000 V

ORH 3700 V* 4500 V* 3000 V 500 V

ORL 2300 V* 3800 V* 5000 V 5000 V

Breakdown voltages testing up to 5000 V (* indicates not well insulated ext. wires)

1000 - 2000 V

0 - 500 V

2000 - 3680 V

> 3680 V

▪ Coil 8

▪ 2 thermal

cycles

▪ ~50 quenches

OLL 10000 V 10000 V 10000 V 7000 V

OLH 10000 V 3600 V 10000 V 10000 V

ORH 6500 V 8500 V 100 V 600 V

ORL 10000 V 10000 V 8000 V 10000 V

Breakdown voltages testing up to 10000 V

▪ Coil 203, 204, 205, 206

▪ 3 thermal cycles

▪ ~50 quenches

5

MQXFS5 @CERN after cold test

203 204 205 206

OLL 3700 V 3700 V 3700 V 3700 V

OLH 3700 V 3700 V 3700 V 2000 V

ORH 3700 V 3700 V 3700 V 3700 V

ORL 3700 V 3700 V 3700 V 3700 V

Breakdown voltages testing up to 3700 V

Summary: short magnet coils meet actual requirements except for coil 107

1000 - 2000 V

0 - 500 V

2000 - 3680 V

> 3680 V

206

2000 V

2500 V

5000 V

10000 V

up to 10000 V

Short model MQXFS1e: magnet history

6

▪ MQXFS1 - the first 150 mm aperture, 1.5 m long Nb3Sn quadrupole within

the CERN and LARP collaboration

▪ Coils fabricated by CERN (#103 and #104) and LARP (#3 and #5)

▪ Electrical checkout after fabrication: no issues up to 2500 V

▪ Five tests performed since 2016

▪ 119 spontaneous quenches

▪ 230 provoked quenches and trips (I>1 kA)

▪ Total of 8 thermal cycles (not counting the latest one for the hi-

potting tests).

7

Short model MQXFS1e: He gas Hi-pot tests

• CLIQ leads used for heater and coil connections• The CLIQ lead from the magnet connected to CL2

• OL heaters (8 strips) in coils 3 & 103 connected to CL3

• OL heaters (8 strips) in coils 5 & 104 connected to CL1

• Hi-pot tests at selected temperatures up to selected voltages (800, 1500 V)

Heater to coil

voltage CL1

Heater to coil Voltage

CL3

1.9 K 2300 V 2300 V

75 K 800 V (test 1)

1500 V

800 V (test 1)

1500 V

150 K 800 V (test 1)

1500 V

800 V (test 1)

1500 V (failed at flattop)

300 K 800 V (test 1)

1200 V

1360 V

800 V (test 1)

970 V

8

Short model MQXFS1e: 300 K in air (after He

gas tests)

▪ The shorted heater was in the group that failed 150 K and

300 K hipot in He

▪ Meet requirements at ambient T in air (after a thermocycle)

▪ 4 QH/coil: survivability of ~100% at 800V and ~94% at

1,500V at 150 K.

QH 3 (CL3) 103 (CL3) 5 (CL1) 104 (CL1)

OL1 460 V 460 V 460 V 460 V

OH2 short 460 V 460 V 460 V

OH3 460 V 460 V 460 V 460 V

OL4 460 V 460 V 460 V 460 V

MQXFAP1, MQXFAP2, LONG MIRROR

9

MQXFAP1

P2, P3, P4, P5 coil

▪ 18 Quenches

▪ 3 thermocycles

MQXFAP2

102, 104, 105, 106 coils

▪ 29 quenches

▪ 1 thermocycle

LONG MIRROR

P1 coil

▪ 22 training quenches

▪ 30 QH induced quenches

▪ thermocycles

Electrical check out after coil fabrication: no issues but tested all < 3680

Coil autopsy after He: coil P1 (Mirror)

10

QH P01

OL1 3700 V

OH2 1500 V

OH3 2070 V

OL4 2340 V

500 - 2000 V

0 - 500 V

2000 - 3680 V

> 3680 V

OL1

OH2

OH3

OL4

RELE

First breakdown voltages testing up to 2500-3700 V

after test in He: coil P5 (MQXFAP1)

11

QH P05

OL1 2380 V

OH2 shorted

OH3 2290 V

OL4 2820 V

First breakdown voltages testing up to 6000 V

1000 - 2000 V

0 - 1000 V

2000 - 3680 V

> 3680 V

OL1

OH2

OH3

OL4

QH to coil Hi-Pot before testing up to 3000 V

P5 First Failure after warmup 2380 V @ OL-LF 2.38kV

Short in heaters 1 and 2

0 2 4 6 8 10 12

1500

2000

2500

3000

3500

4000

4500

5000

5500

heater1

heater2

heater3

heater4

Hip

ot fa

ilure

vo

lta

ge

(V

)

Hipot voltage failure index

MQXFAP2 after He

12

First breakdown voltages testing up to 1500 V

6 out of 8 heater circuits passed the test

Heater circuit 3 failed at 1.4 kV (arc-fail,

116.5 μA leakage current)

Heater circuit 4 failed at 1.5 kV (arc-fail,

92.3 μA leakage current)

Each single heaters passed the Hi-pot test up to 460 V afterwards

Coil 108 short samples QH test

13

QH 108 long piece

OL1 6000 V

OH2 6000 V

OH3 6000 V

OL4 6000 V

108 coil: before He test passed hi-pot up to 6000 V

LQS03 model

14

▪ Each heater covers half length, and full width of the surface

where it is applied

▪ Each coil has four heaters:

▪ 2 OL heaters (one on return end, one on lead end)

▪ 2 IL heaters (one on return end, one on lead end)

▪ Polyimide thickness: 25 µm

▪ 41 training quenches

▪ 4 trips

▪ Thermocycles:

15

LQS03 hi-pot results after cold test

COIL 18 COIL 16 COIL 19 COIL 15

Lead end, OL 2.11 kV (BD) 2.47 kV (BD) 1.92 kV (A) 2.47 kV (BD)

Return end, OL 1.61 kV (A) 1.71 kV (A) 1.55 kV (A) 3.46 kV (A)

Lead end, IL 1.41 kV (A) 1.21 kV (A) 1.64 kV (A) 1.12 kV (A)

Return end, IL 1.31 kV (A) 1.61 kV (A) 1.42 kV (A) 1.47 kV (A)

Breakdown voltages testing up to 6000 V (OL), 2000 V (IL)

▪ All heater passed the 650 V (max coil to heater voltage

seen by the magnet) Hipot test after breakdown test

500 - 2000 V

0 - 500 V

2000 - 3680 V

> 3680 V

Summary of first failure Hipot

16

0 50 100 150 200 250 300 350

0

2000

4000

6000

8000

10000 #9

MQXFAP1 (coil 5)

MQXFAP2

MQXFS5

Long MIrror (coil 1)

MQXFS3 (coil 8)

MQXFS3

MQXFS1

Passed hipot test

Co

il-h

ea

ter

failu

re v

olta

ge

s (

V)

# of quenches

#13