Brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT LHC IR Quad Heaters.

brookhaven - fermilab - berkeleyUS LHC ACCELERATOR PROJECT

LHC IR Quad Heaters


Michael Lamm 2

Schematic of LHC Inner Triplet 4 IP x (2 Triplets/IP)=8 Circuits

-Q1 and Q3 made by KEK, Q2 made by Fermilab. Q1 and Q3 opposite polarity of Q2.

- “ FNAL” Q2 consists of two 5.5m magnets bussed in series and contained in a single cryostat

- Series of 8 model magnets + one full scale prototype.

DFBX MCBXB MQSXA BPM MCBXA MCBXn BPM To IP

Q Q3 Q2b Q2a Q1D1

- FNAL - KEK - CERN - LBNL -BNL


Michael Lamm 3

Quench Protection Test on Model Magnets

Magnet Protection Requirements: -Peak Temperature <400K -Peak Voltage to Ground <1000 V

Heater Parameters:

-Heater Insulation

-Heater Width

-Resistance Distribution

-Heater Location

Protection Parameters-Quench detection threshold 300-500 mV -Strip heaters provide primary protection NO EXTERNAL ENERGY EXTRACTION-Redundancy two circuits (H1&H3, H2&H4)-Simulate CERN Heater Circuit: 7 mF, 900 V voltage, RC~100mS, Peak Power >20 W/cm2


Michael Lamm 4

Magnet Position Element (all 25 m thick) Insulation

HGQ01 Inter Stainless steel 15.9mm wide 325uM

Outer None N/A

HGQ02 Inter Stainless steel 15.9mm wide 325uM

Outer Stainless steel 15.9mm wide 350uM

Inter Stainless steel 15.9mm wide 325uM

Outer 15.9 mm wide with copper plating 38 mm etched areas at 114 mm intervals. 350uM

HGQ06 Inter None N/A





Outer 15 mm wide with copper plating 120 mm etched areas at 360 mm intervals. 250uM


Outer 15 mm wide with copper plating 102 mm etched areas at 204 mm intervals. 225uM

HGQ03 & HGQ05

Location Outer coil 2 mm from midplane

Material Copper plated stainless steel

Copper thickness 4 m

SS thickness 25 m

Copper Plating 102 mm etched areas at 306 mm intervals

Width 15 mm

Insulation to Coil 225 m

MQXB

Quench protection program


Michael Lamm 5

Two design Parameters: Heater Location and Distributed Resistance

Inter Layer Vs. Outer Layer

-Outer layer heaters are easier to install

-Inter layer heaters might be more effective

Longitudinal Resistance Distribution

-Power supply specs are fixed, so..what is more important: larger area coverage or higher peak power?

Outer Layer

Inter Layer

210 mm(with copper plating)

105 mm(without

copper plating)

15 mm9 mm

.21 mm


Michael Lamm 6

Using Quench Integral to Study Two Heater Parameters

Outer heaters just as effective as inner

Quench detection times significant part of quench integral

Longitudinal resistance distribution works

0.0

5.0

10.0

15.0

20.0

0 0.2 0.4 0.6 0.8 1I/Ic

Qu

ench

In

teg

ral

MII

T's

HGQ08 55 W/cm**2HGQ09 22 W/cm**2HGQ09 45 W/cm**2HGQ08 22 W/cm**2

Inner vs.Outer Heaters

Longitudinal Resistance Distribution

MIItsdTT

TcAdttIQI

peakT

T Cu

pcompt

0

''

'

11010 26

0

26


Michael Lamm 7

Peak Temperature (use spot heaters that simulate spontaneous quenches)

0

50

100

150

200

250

300

350

400

2.0 4.0 6.0 8.0 10.0 12.0 14.0Current (kA)

Mea

sure

d P

eak

Tem

per

atu

re (

K)

HGQ07 50 W/cm**2

HGQ08 50 W/cm**2

HGQ09 22 W/cm**2

HGQ09 45 W/cm**2

HGQ09 no. 2 45 W/cm**2

Most

pessimistic

quench location tested

with spot heater.

Spot heater quenches in pole turn

0

50

100

150

200

250

300

350

2 4 6 8 10 12 14Current (kA)

Me

as

ure

d P

ea

k T

em

pe

ratu

re (

K)

Outer Pole

Inner Pole


Michael Lamm 8

Voltage to Ground

For 1.9 M model, voltage to ground is low, less than 30 Volts at peak operating field gradient...

0

40

80

120

2000 5000 8000 11000 14000

Current (A)

Pe

ak

Vo

ltag

e (

V)

Opposite heater circuit

Adjacent heater circuit

Stainless Steel Only Heater

The eight coils that make up a HGQ magnet are bussed in series, with inner to outer pole turn splice. Voltage to ground is largely due to resistive-inductive (im)balance between inner and outer coils

imbalanced heater geometry


Michael Lamm 9

Protection Conclusions

Heaters

-Heaters adequately protection magnet from excessive peak temperatures and peak voltage to ground

-Outer layer heaters are just as effective as interlayer heater. Outer layer heaters chosen for ease of installation

-Reducing insulation doesn’t seem to have much effect (or small compared to other variables

-Increasing peak power is more important than longitudinal resistance: use HGQ08 style heater

Bus Work

-Parameterize temperature and velocity

-Single layer stabilizer is adequate. Opt for 1 layer of copper

Brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT LHC IR Quad Heaters.

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