Quench calculations calculations for for the the Super Super- - - PowerPoint PPT Presentation

Quench Quench calculations calculations for for the the Super Super-

• FRS

FRS quadrupoles quadrupoles

• E. Floch. FAIR/MT.11 March09
• Studied magnets: short and long quadrupoles designed by CIEMAT (22 Jan. 2009)
• Brief presentation of the magnets (stored energy, estimated resistive voltage)
• Limits for the hotspot temperature and maximum coil to ground voltage
• Use of the M. Wilson's quench program
• Estimation of longitudinal and transverse propagation velocities based on measurements
• Validation of the quench program on 2 real magnets
• Quench calculations for the short quadrupole (without and with dump resistor)
• Quench calculations for the long quadrupole (without and with dump resistor)
• Conclusions

Super Super-

• FRS

FRS quadrupole (CIEMAT quadrupole (CIEMAT design design, , January January 2009) 2009)

4.85 Bmax (T) 450 I0 (A) 11.9 L(450A) (H/m) 1026 total n° of turns 27 n° of turns per layer 38 n° of layers

• E. Floch. FAIR/MT.11 March09

0.1 insulation thickness between layers (mm) 3.06 Tcs-4.2 (K) 0.27 I0/Ic(4.2K,Max) 1900 Ic(4.2K,4T)_min (A) 1600 Ic(4.2K,5T)_min (A) > 70 RRR 2.4 Cu/Sc 0.04 Conductor insulation thickness (mm) 1.18x1.88 Bare Conductor size (mm*mm) 1.18 Bare conductor tickness (mm) 1.88 Bare conductor with (mm)

Stored Stored Energy Energy

• E. Floch. FAIR/MT.11 March09

744 266 130 200 753 1205 1205 E/length (kJ/m) 92 42 18 27 94 149 129 E/V1pole (MJ/m3) 0.004024 0.004454 0.00399 0.015618 0.009625 0.00968 0.00749 V1pole (m3) 2395 2716 35*55 50*55 46.8*50.74 52.92*51.69 52.92*51.68 Coil cross section=wa*wr (mm*mm) 31 52 54 36 V=L*I0/120 (V) 372 189 70 420 904 1446 964 E (kJ) 4.5416 30.6513 6.95 16.74 21.2 14.28 9.52 L_I0 (H) 404.5 110.9 142 224 292 450 450 I (A) 1.68 1.64 1.68 6.576 3.5 3.54 2.74 average turn length (m) 0.503 0.71 0.54 2.1 1.2 1.2 0.8 magnetic effective length (m) MSU quad QD MSU quad QE big-Ribs Q500 Super-FRS dipole Toshiba long quad CIEMAT long quad CIEMAT short quad Superferric magnet

The Super-FRS quadrupole has an energy per unit length (J/m) and a "pole" energy density (J/m3) which is 60 % higher than the biggest MSU quadrupole.

" "Quench Quench" " specification specification

• E. Floch. FAIR/MT.11 March09
• The quench protection scheme is designed so that the hotspot temperature (Tm) and the maximum coil to ground

voltage (Vcgm) stay below secure limits.

• For a potted magnet with a fiber glass and resin insulation, most of the magnet designers choose Tm < 300 K.
• The European law for AC applications states that Vtest = 2*Vmax+500 V.
• The initial intention for the Super-FRS was to keep Vmax = 2*Vcgm = 750 V

so that the coil to ground insulation is tested at 2000 V at 4 and 300 K. (this values was applied for the design of the Super-FRS dipole) . One can imagine extend Vtest up to 2500 or 3000 V in order to allow Vcgm up to 1000 or 1250 V.

yes 2500 1000 300 possible extention no 2000 750 300 initial and actual yes 3000 1250 300 possible extention use of dump resistor for protection Vtest_4 and 300K (V) Vcgm (V) Tm (K) Spefication

Orders of Orders of magnitude magnitude

• E. Floch. FAIR/MT.11 March09

411 2002 1145 (Rq(t)*I)max close to Rq(Tav)/2*I0/2 (V) 8.1 17.6 10.0 Rq(RRR=100, Tav,B=0) (ohm) (will be close to Rqmax) 73 154 126 Tav (K) dipole long quad short quad Super-FRS magnets

• When the magnetic stored energy is used to heat up one pole homogenously,

the corresponding temperature is Tav

• The hotspot temperature Tm will be higher than Tav
• The maximum quench resistance will be close to R1pole(Tav)
• The maximum resistive voltage will be of the order of R1pole(Tav)/2*I0/2

In the long quadrupole, we can already expect a resistive voltage 2* higher than in the short quadrupole 5 * higher than in the dipole

Use of M. Wilson quench program

• E. Floch. FAIR/MT.11 March09

One version of M. Wilson quench program was given to GSI by B. Hassenzahl We introduced the following modifications:

• ρ(RRR, B, T) instead of ρ(RRR=60, T)
• Tm computed with Bm and Rq computed with Bav = Bm/2
• The original program of M. wilson does not take into account the magneto-resistance
• For the Super-FRS quadrupole (with Bm = 4.85 T), forgetting it would lead to underestimate by 100 K the hotspot

temperature in case Miits = 0.49E6 A2.s

50 100 150 200 250 300 350 400 0.1 0.2 0.3 0.4 0.5 0.6 Miits (1E6A2.s) T (K) Miits_B=0 (1E6A2.s) Miits_B=4.85T (1E6A2.s)

Miits curves for the Super-FRS quadrupole conductor

M.

• M. Wilson's

Wilson's longitudinal longitudinal propagationvelocities propagationvelocities

• E. Floch. FAIR/MT.11 March09
• The program uses as input parameters the longitudinal (Vpfl) and transverse (Vpfa, Vpfr) quench propagation velocities
• The program can either computes these velocities itself or the user chooses them
• M. Wilson formulation

He share share share strands strands strands pfW

T T T L T Cp A t I t V − ⋅ ⋅ = ) ( 1 ) ( ) (

_

2 / ) ) , ( ( Tc B I T T

cs share

+ =

0.0E+00 4.0E+04 8.0E+04 1.2E+05 1.6E+05 4 9 14 19 T (K) (J/m3.K) Cp_Cu_Wilson (J/m3.K) Cp_Cu_CERN (J/m3.K) Cp_NbTi_Wilson (J/m3.K) Cp_NbTi_collins (J/m3.K)

Volumetric specific heat Use of CpNbTiW (Wilson) or CpNbTiC (Collins)

Wire 1 diam = 0,686 mm, alpha= 1.8

20 40 60 80 50 100 150 200 250 300 350 400 I (A) (m/s)

Vpf_4T (m/s) Vpf_2T (m/s) VpfW_CpNbTiW_4T (m/s) VpfW_CpNbTiW_2T (m/s) VpfW_CpNbTiC_4T (m/s VpfW_CpNbTiC_2T/2.4 (m/s)

• Better fit of experimental values with CpNbTi Collins
• Computed velocities may give the good order of magnitude

and should not be taken as "accurate" computations

• Propagation velocities must be measured

Estimation of quench propagation velocities (Vpf)

• E. Floch.GSI Quench expert meeting. Oct 2008

Vpf influenced by dT/dt at the normal front and Tcs-THe.

20 40 60 80 0.5 1 1.5 2 2.5 3 3.5 4 4.5 Tcs-THe (K) (m/s) Vpfmeasured_0T (m/s) Vpfmeasured_1.63T (m/s) Vpfmeasured_4.22T (m/s)

NbTi Cu NbTi Cu Cu NbTi Cu Cu

A A with A A A I Cp Cp T B RRR dt dT / ) ( 1 1 1 ) , , (

2

= + ⋅ ⋅ ⋅ + + ⋅ + ⋅ = α α α α ρ

Vpf influenced by: B, I2/(ACu*(ACu+ANbTi) and Tcs-THe.

16 12 9.3 33 8.7 26 13

Vpf (m/s)

1.3 1.20 1.4 1.2 2.3 1.2 2.3

Tcs-THe (K)

8.2E+05 3.8E+05 2.0E+05 6.8E+05 1.7E+05 7.7E+05 5.6E+05

I2/(ACu*(ACu+ANbTi)) (A2/mm4)

4 6 6 4.22 4.22 7.8 6.7

B (T)

4.2 4.2 4.2 4.2 4.2 1.9 1.9

THe (K)

measurements published in litterature on Cu wire at 4.2K

LHC_outer LHC_outer "

Considering measurements made on other Cu wires at 4 K:

• we could estimate: 10 < Vpf < 30 m/s for the LHC outer cable
• which fits with measurements: 13 < Vpf < 26 m/s

Estimation method validated on one example

Measured on wires with Cu matrix

Estimation of transverse quench velocities (Vpft)

• E. Floch.GSI Quench expert meeting. Oct 2008

Experimental work done on single layer solenoids where Vpfl and Vpft were measured Measured on one solenoid (in a background field) Summary of measurements

Vpf and Vpft for the ctd 6 kJ dipole (MSU)

• E. Floch.GSI Quench expert meeting. Oct 2008

47.0 AFRP (%) 46.4 ACu(%) 2200 n° of turns 6.6 ANbTi (%) 3 B (T) 7 Cu ratio 6.02 E (kJ) 0.48 Insulated diameter (mm) 50 I (A) 0.445 bare diameter (mm) 4.82 L (H) 35 33 10 ? Vpf measured (m/s) 1.2 1.2 3.5 1.2 Tcs-T0 (K)

8.9E+5 6.8E+5 7.2E+4 1.2E+05

I2/(ACu*(ACu+ANbTi)) (A4/mm4) 4 4.22 2.4 3 B (T) Measured in literature ctd dipole

From measurements in literature, we can estimate: 10 < Vpf < 35 m/s

• 0.05

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4

• 0.01

0.01 0.02 0.03 0.04 0.05 0.06 t (s) (V) V_1pole=Rq(t)*I+L/2*dI/t_measured (V)

Recorded quench voltage (Vq)

I V n A K B RRR dt dV

pf q Cu

⋅ ⋅ ⋅ ⋅ = 2 ) 10 , , ( ρ 10.5 4 10.0 from 32 to 42 ms 34 14 10.5 3 7.5 from 28 to 32 ms 48 10 10.5 2 5.0 from 18 to 28 ms 27 18 9.3 1 2.2 from 0 to 18 ms Vpft (mm/s) Δtqt (ms) Vpf_3T (m/s) nq dV/dt (V/s) nq : n° of quench initiating points (courtesy A.L. Zeller)

Quench calculations on the ctd 6 kJ dipole

• E. Floch.GSI Quench expert meeting. Oct 2008

10 20 30 40 50 60 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 t (s) (A) 2 4 6 8 10 12 (ohm)

I_QHE_rho(RRR=100,1.5T,T)_ 10 m/s_g=0.003 (A) I_measured (A) Rq_QHE_(RRR=100,1.5T,T)_ 10 m/s_g=0.003 (ohm) R_measured (ohm)

30 27 < < 48 Vpft (mm/s) 10 9.3 < < 10.5 Vpf (m/s) used in program measured

The quench program was validated on a 6 kJ dipole when using measured quench propagation velocities

Super-FRS dipole test coil

• E. Floch.GSI Quench expert meeting. Oct 2008

1.99 mm 1.18 mm For test coil according to IPP conductor initial Conductor insulation (G10) 0.125 mm thick CR_model_coil.cdr 0.15 mm (Wu Weiyu 08.Au08) 2.24 mm (Wu Weiyu. 08.Au08) 2.54 mm (Wu Weiyu. 08.Au08) 1.43 mm (Wu Weiyu 08.Au08) 1.73 mm (Wu Weiyu . 08.Au08)

Wrapping the G10 ground insulation (Spring 2007)

224 413 I (A) 28 22 n° of layers 20 20 turns/layer 420 (dipole with iron) 54.9 E (kJ) 1.29 1.6 Bmax_conductor (T`) 6.576 6.515 turn length (m) Prototype coil test coil

Quench Quench measurement measurement for for the the Super Super-

• FRS

FRS dipole dipole test test coil coil

13 < < 15 Vpfa=Vpfr used by the quench progarm to fit the experimental curve (mm/s) > 25 Vpfa = Vpfr deduced from temperature sensor placed on coil (mm/s) 34.5 < < 95.5 Vpfa=Vpfr deduced from literature (mm/s) 0.0115 Vpfa/Vpf= Vpfr/Vpf deduced from literature 1 < < 4 Vpf used by the quench progarm to fit the experimental curve (m/s) > 1.4 Vpf = deduced from temperature sensor placed on coil (m/s) 3 < < 8.3 Vpf estimated from measurements in literature (m/s) 8.3 Vpf computed with Wilson's formulation and Collins specific heat= VpfWc (m/s)

• E. Floch. FAIR/MT.11 March09
• 50

50 100 150 200 250 300 350 400 450

• 1

1 2 3 4 5 6 7 8 t (s) (A) I_measured (A) I_computed_Vpfl=2m/s_Vpft=0.013m/s (A) I_computed_Vpfl=1m/s_Vpft=0.015m/s (A) I_computed_Vpfl=3m/s_Vpft=0.013m/s (A) I_computed_Vpfl=4m/s_Vpft=0.013m/s (A) I_computed_Vpfl=1.5m/s_Vpft=0.0135m/s (A)

Estimated Estimated quench quench velocities velocities for for the the Super Super-

• FRS

FRS quadrupole quadrupole

(1, 3.6, 3) < < (10, 144, 120) (Vpfa,Vpfr,Vpf) (m/s, mm/s, mm/s) 0.003< <0.012 Vpfr/Vpf 0.00365< <0.0144 Vpfa/Vpf 1.22 Vpfa/Vpfr 1 < < 10 Vpf (m/s)

• E. Floch. FAIR/MT.11 March09

Estimated velocities from measurement in the literature

25 50 75 100 125 150 2 4 6 8 10 12 Vpf (m/s) (mm/s)

Vpfr_estimated (mm/s) Vpfa_estimated (mm/s) Computed with M. Wilson's formulation: VpfW = 16.1 m/s and VpfWC = 6 m/s

Voltages Voltages of

• f importance

importance and and location location

• E. Floch. FAIR/MT.11 March09
• Vqm = max(Rq*I): the maximum quench voltage (Rq is the quench resistance),
• Vcgm the maximum coil to ground voltage (determines the necessary thickness of the ground insulation)
• Vttm: maximum turn to turn voltage within one layer (related to the conductor insulation thickness)
• Vllm: maximum layer to layer voltage (related to the corresponding conductor and interlayer insulation thickness)
• Vvtm: maximum voltage seen by one of the 3 voltage taps connected to the quadrupole

(determines the insulation level of the quench electronics)

Rd +Rd*I(t)/2

• Rd*I(t)/2

(x) (x) Voltage Voltage C C B B D D E E A A 1 pole 1 pole Voltage profile for a high value of Rq Voltage profile for a low value of Rq Voltage profile with quench Still superconducting Still superconducting Quenched Quenched

(Vcg_quench.cdr)

Vcgm(t) = = Rd*I(t)/4+3/4* Rq(t)*I Rd*I(t)/2 + Rq(t)*I+L/4*dI/dt Rq Rq Vcgm(t) = = 3/4* Rq(t)*I Rq*I(t)/2 +L/4*dI/dt : voltage taps for quench detection

Vcgm will be see at point A or B Vvtm will be seen at point A or C

Short quadrupole Short quadrupole without without dump dump resistor resistor (Rd= 0) (Rd= 0)

100 200 300 400 500 0.5 1 1.5 2 2.5 3 3.5 4 t (s) (A) or (K) 400 800 1200 1600 2000 (V) I(A) Tm (K) Rq*I(V)

• E. Floch. FAIR/MT.11 March09

Vpf =10 m/s, Vpfa =73 mm/s, Vpfr = 60 mm/s (average transverse velocities), Rd=0

100 200 300 400 500 0.5 1 1.5 2 2.5 3 3.5 4 t (s) (A) or (K) I_RRR=280 (A) Tm_RRR=280 (K) I_RRR=200 (A) Tm_RRR=200 (K) I_RRR=100 (A) Tm_RRR=100 (K)

The RRR has a little influence on Tm We will take for all the other calculations RRR = 100

RRR=100,

Short Short quad quad., ., hotspot hotspot temperature temperature (T (Tm

m)

) versus versus quench quench velocities velocities

• E. Floch. FAIR/MT.11 March09

25 50 75 100 125 150 5 10 15 20 Vpf (m/s) (mm/s) Vpfa_Tm=300K (mm/s) Vpfr_Tm=300K (mm/s) Vpfr_estimated (mm/s) Vpfa_estimated (mm/s) area with Tm > 300 K area with Tm < 300 K

For half of the estimated volume (Vpf, Vpfa, Vpfr), we have Tm > 300 K which would require the use of a dump resistor

Short Short quad quad., ., maximum maximum coil coil to to ground ground voltage voltage (V (Vcgm

cgm)

) versus versus quench quench velocities velocities

• E. Floch. FAIR/MT.11 March09

200 400 600 800 1000 1200 1400 1600 1 2 3 4 5 6 7 8 9 10 Vpf (m/s) (K) or (V)

Tm_ga=0.00365_gr=0.003 (K) Vcgm_ga=0.00365_gr=0.003 (V) Tm_ga=0.01095_gr=0.009 (K) Vcgm_ga=0.01095_gr=0.009 (V) maximum transverse velocities minimum transverse velocities

• For more than half of the (Vpf, Vpfa, Vpfr) volume, we have 1000 < Vcgm < 1400 V
• There is no (Vpf, Vpfa, Vpfr) triplet giving Tm < 300 K and Vcgm < 1000 V
• To get Tm < 300 K and Vcgm < 750 or 1000 V, a dump resistor is needed

Short Short quad quad., ., use use of a

• f a dump

dump resistor resistor (R (Rd

d)

)

100 200 300 400 500 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 t (s) (A) or (K) I_RRR=100_Rd=1ohm (A) Tm_RRR=100_Rd=1ohm (K) I_RRR=100_Rd=0 (A) Tm_RRR=100_Rd=0 (K)

• E. Floch. FAIR/MT.11 March09

RRR=100, tRd = 230 ms, Vpf = 4 m/s, Vpfa = 29.2 mm/s, Vpfr = 24 mm/s (average transverse velocities)

200 400 600 800 1000 1200 1400 1600 1800 1 2 3 4 5 t (s) (A)

Vcgm=(Rd+3Rq)/4*I_Rd=1ohm (V) Rq*I_Rd=1ohm (V) Vcgm=3/4*Rq*I_Rd=0 (V) Rq*I_Rd=0 (V)

In that particular case, using Rd= 1 Ω enables to reduce Tm from 458 to 351 K and Vcgm from1260 to 736 V.

Short Short quad quad., ., used used of a

• f a dump

dump resistor resistor (R (Rd

d)

)

• E. Floch. FAIR/MT.11 March09

300 600 900 1200 1 2 3 4 Rd (ohm) (K) or (V) Tm (K) Vcgm (V) Vvtm (V) Vpf=4m/s, Vpfa=14.6 mm/s, Vpfr=12mm/s

In that example Rd = 2.4 ohm gives Tm = 300 K For each (Vpf, Vpfa, Vpfr) triplet, it is possible to find Rd so that Tm = 300 K (Lowest transverse velocities)

Short Short quad quad., ., used used of a

• f a dump

dump resistor resistor (R (Rd

d)

)

• E. Floch. FAIR/MT.11 March09

200 400 600 800 1000 1200 1 2 3 4 5 6 7 8 9 10 Vpf (m/s) (V) 1 2 3 4 5 6 (ohm)

Vcgm (V) Vvtm (V) Rd (ohm) Vpfa/Vpf =0.00365, Vpfr/Vpf= 0.003

For the lowest transverse propagation velocities, it is possible to have: Tm = 300 K and Vcgm < 1000 V by properly choosing Rd between 1 and 4.5 ohm The following simulations give the value of Rd that corresponds to Tm = 300 K

(Lowest transverse velocities)

Long quadrupole Long quadrupole without without dump dump resistor resistor (Rd= 0) (Rd= 0)

• E. Floch. FAIR/MT.11 March09

100 200 300 400 500 1 2 3 4 5 t (s) (A) or (K) 600 1200 1800 2400 3000 (V)

I(A) Tm (K) Rq*I(V) Vcgm (V) Vvtm (V)

RRR=100, Vpf = 10 m/s, Vpfa = 36.5 mm/s, Vpfr = 30 mm/s (lowest transverse velocities)

Short and Short and long long quadrupoles quadrupoles without without dump dump resistor resistor

• E. Floch. FAIR/MT.11 March09

200 400 600 800 1000 1200 1 2 3 4 5 6 7 8 9 10 Vpf (m/s) (K) Tm_Short_Quad_ga=0.00365_gr=0.003 (K) Tm_Short_Quad_ga=0.01095_gr=0.009 (K) Tm_Long_Quad_ga=0.00365_gr=0.003 (K) Tm_Long_Quad_ga=0.01095_gr=0.009 (K) Lowest transverse velocities Highest transverse velocities

• Tm only increases from 25 to 140 K when we change from the short to the long quadrupole.
• This relatively small increase is due the fact that the half turn length is only increased by 0.4 m.
• With Vpf = 10 m/s, this 0.4 m induces a delay of 40 ms in the time needed to completely quench the coil.

This delay is very low compared to the 5 s of the current decay and do not increase Tm much.

Short and Short and long long quadrupoles quadrupoles without without dump dump resistor resistor

• E. Floch. FAIR/MT.11 March09

500 1000 1500 2000 2500 1 2 3 4 5 6 7 8 9 10 Vpf (m/s) (V) Vcgm_Short_Quad_ga=0.00365_gr=0.003 (V) Vcgm_Short_Quad_ga=0.01095_gr=0.009 (V) Vcgm_Long_Quad_ga=0.00365_gr=0.003 (V) Vcgm_Long_Quad_ga=0.01095_gr=0.009 (V) Lowest transverse velocities Highest transverse velocities

• Vcgm =is from 450 to 650 V higher for the long quadrupole.
• As the short quadrupole, the long quadrupole also requires a dump resistor.

Long quadrupole Long quadrupole with with dump dump resistor resistor

• E. Floch. FAIR/MT.11 March09

200 400 600 800 1000 1200 1400 1600 1800 2000 1 2 3 4 Rd (ohm) (V) or (K)

Tm (K) Vcgm (V9 Vvtm (V) Vpf=10 m/s, Vpfa/Vpf = 0.00365, Vpfr/Vpf=0.003 , minimum transverse velocities

• Using Rd = 1.82 Ω enables to reduce Tm from 415 to 300 K and Vcgm from 1913 to 1020 V.
• Using Rd = 3 Ω, it is possible to bring Vcgm to a minimum value of 675 V (let's call it Vcgm_min)

Long quadrupole Long quadrupole with with dump dump resistor resistor

• E. Floch. FAIR/MT.11 March09

200 400 600 800 1000 1200 1400 1600 1 2 3 4 5 6 7 8 9 10 Vpf (m/s) (V) 1 2 3 4 5 6 7 8 (ohm) Vcgm_min_highest_transverse_velocities (V) Vcgm_min_lowest_transverse_velocities (V) Rd_highest_transverse_velocities (ohm) Rd_lowest_transverse_velocities (ohm) 132 < Tm < 300 K

By properly choosing Rd, it is possible to reach a minimum value of Vcgm and have Tm < 300 K

• For 2 < Vpf < 10 m/s, choosing Rd between 1.5 and 7 Ω enables to have Vcgm < 1000 V.
• For Vpf = 1m/s and the lowest transverse velocities, the time trt to reach 800 mV is 1020 ms for which

Tm(1020s) = 109 K. In order to get 300 K, one has to use a big value of Rd (6.8Ω) which gives Vcgm = Rd*I0/2= 1530 V.

Conclusions Conclusions

• E. Floch. FAIR/MT.11 March09
• The Super-FRS (CIEMAT) long quad. has an energy density 60 % higher than the biggest MSU quad.
• The choice of the initial quench propagation velocities has a very strong influence on Tm and Vcgm
• Propagation velocities can be estimated from measurements on other wires or cables
• For the estimated velocities, there no possibility to have both Tm < 300 K and Vcgm < 750 V

which leads to the necessity of using a dump resistor (Rd)

• Knowing the quench propagation velocities, it is possible to choose Rd so that Tm < 300 K and Vcgm < 1000 V

This is achievable for the short quadrupole for all estimated velocities. For the long one, it requires Vpf > 2 m/s

• The CIEMAT design (for the estimated velocities) does not fulfill our initial specification:

Tm < 300 K, Vcgm < 750 V, Rd = 0: self-protecting magnet (magnets tested at 2000 V)

• We could change our specification to: Tm < 300 K, Vcgm < 1000 V, use of Rd (magnets tested at 2500 V)

Before doing so, an internal discussion and contacts with other experts are needed

• If our "quench" specification is changed:
• turn to turn and layer to layer voltages must be tested on a coil mock-up before

the fabrication of the 1st full size quad.

• quench propagation must be measured before or during the fabrication of the 1st full size quad.
• the 1st full size quad. should be equipped with a spot heater
• the actual quench detection scheme (which uses a bridge) would not detect an symmetrical quench

(due to beam losses). With an non-self protecting magnet, such a quench must be detected. This will require a more complex and costly quench electronics.