M.J. Barnes 1

MKI Magnet Design, PT100 Sensor Locations & Heating Observations in 2011

M.J. BarnesAcknowledgements:

H. Day, L. Ducimetiere, N. Garrel

23 November 2011

M.J. Barnes 2

Kicked Beam

TMR connection

entrance box connection

capacitor

ferrite yoke

ground plateground

plate HV plate HV plate

PT100Tube_Dn

Beam impedance reduction ferrite

(lossy + low-loss)

Beam impedance reduction ferrites

(lossy + low-loss)

Damping resistor (now at both ends)

PT100Mag_Dn

PT100Tube_Up

PT100Mag_Up

PT100Tube_Dn

PT100Mag_Dn

PT100Tube_UpPT100

Mag_Up

Screen conductors soldered to “ground”

Screen conductors capacitively coupled to “ground”

An LHC Injection Kicker

23 November 2011

LHC Injection Kicker: Maximum Temperatures During Oct. 2011

Magnet PT100’s are mounted on ground plates: these plates contact the ground busbar and magnet capacitors; Ground busbar does not contact ferrites – hence heat conduction to magnet PT100’s is mainly via magnet capacitors. Hence Mag_Up would be expected to measure a higher temperature than Mag_Dn, but …. Tube_Up temperature > Tube_Dn temperature, maybe because of more cooling at “Dn” end (due to SS tube and “cage” around ferrites??).The Power (W/m) shown is derived from impedance measurements – measured magnet temperature does not correlate with the power….

Kicked Beam

TMR connection

entrance box connection

capacitor

ferrite yoke

ground plateground

plate HV plate

HV plate

PT100Tube_Dn

Beam impedance reduction ferrite

(lossy + low-loss)

Beam impedance reduction ferrites

(lossy + low-loss)

PT100Mag_Dn

PT100Tube_Up

PT100Mag_Up

Screen conductors soldered to “ground”

(Ferrites mounted on SS tube)

Screen conductors capacitively coupled to “ground”

(metallization on ceramic tube)

NO Capacitor

here

23 November 2011 3M.J. Barnes

MKI2 Mag_Up Mag_Dn Tube_Up Tube_Dn Tank Power (W/m)A 42.2 38.8 76 51.1 8 60B 44.1 40.9 70.3 50.2 10 97C 38.8 41.6 66.5 58.6 4 76D NC NC NC NC 9 89

MKI8 Mag_Up Mag_Dn Tube_Up Tube_Dn Tank Power (W/m)A 36.6 NC 73.1 35.4 1 88B 40.9 57.7 88.3 56.7 3 Not meas.C 45.2 40.9 102.1 64.7 2 Not meas.D 43.1 68.3 72.4 67.9 6 Not meas.

M.J. Barnes 4

y = 7.39E-10x + 2.04E-07R² = 9.98E-01

y = 3.79E-09x + 3.25E-07R² = 1.00E+00

6.00E-07

6.10E-07

6.20E-07

6.30E-07

6.40E-07

6.50E-07

6.60E-07

6.70E-07

6.80E-07

6.90E-07

7.00E-07

7.10E-07

2.580E-07

2.600E-07

2.620E-07

2.640E-07

2.660E-07

2.680E-07

2.700E-07

2.720E-07

2.740E-07

2.760E-07

2.780E-07

2.800E-07

75 77.5

80 82.5

85 87.5

90 92.5

95 97.5

100

50%

Del

ay (s

)

TMR

Volt

age

Rise

Tim

e (s

)

Magnet Inductance Scale Value (%)

Predicted 5% to 95% rise-time versus magnet Inductance

RISE_TIMEC(V(MagOut)*50kV/250,1.25k,23.75kV)

XVALUE_AT_YV(V(MagOut)*50k/250,12.5k)-XVALUE_AT_YV(V(MagIn)*50k/250,12.5k)

Terminating Resistor

Transmission Line

Z

Magnet

Z

Z

Main Switch

PFN or PFL

Z

RCPS

Dump Switch

Dump ResistorZ

LcLc

Cc/2Cc/2Cc/2

Lc

Cc/2Cc/2

Lc

Cc/2Cc/2

0

Cc/2

(#1) (#2) (#n)(#[n-1])

LHC Injection Kicker: System Overview

Lc is defined by the magnetic circuit, i.e. dimensions of aperture, but also deceases with reducing ferrite permeability; Rise-time decreases with reducing Lc and/or Cc (~0.7ns reduction in rise-time, per 1% reduction in cell inductance). Delay decreases with reducing Lc and/or Cc (~3.8ns reduction in delay, per 1% reduction in cell inductance).

Delay m n Lc Cc

1

4cf

Lc Ls Cc

TMR Current

23 November 2011

0

0.5

1

1.5

2

2.5

3

3.5

4

85 90 95 100 105 110 115 120 125 130 135 140 145

Ind

uc

tan

ce

(μH

)

Average of Magnet Input Face and Output Face Temperature During Cool down (˚C)

33 cells * 101nH/cell

106˚C

LAB measurement: Magnet in vacuum tank; tank at atmospheric pressure; no bake-out jacket.

M.J. Barnes 5

MKI8 Measured Temperature (MagD_Dn) & Rise-Time (all 4 TMRs): October 2011

2022242628303234363840424446485052545658606264666870

0.695

0.696

0.697

0.698

0.699

0.7

0.701

0.702

0.703

0.704

0.705

0.706

0.707

0.708

0.709

0.71

Tem

per

atu

re [˚C

]

TMR

5%

to

95%

Ris

eTim

e (µ

s)

Date & Time

MKI8 SoftStart (Average RiseTimes 7.0us + (7points), 53.3kV)

MKI.UA87.IPOC.AB2:T_RISETIMEMKI.UA87.IPOC.BB2:T_RISETIMEMKI.UA87.IPOC.CB2:T_RISETIMEMKI.UA87.IPOC.DB2:T_RISETIMEMKI8 SS: Average RiseTimeMKI.D5R8.B2:TEMP_MAGNET_DOWN

The rise-time of TMR current, for MKI8D, decreases at elevated temperatures (>~60˚C measured) for MKI8D_Dn.

23 November 2011

Analysis of MKI8 measurements

y = -2.410E-04x + 5.269E+01R² = 5.360E-01

y = -2.251E-04x + 5.269E+01R² = 2.186E-02

52.664

52.666

52.668

52.670

52.672

52.674

52.676

52.678

52.680

52.682

52.684

52.686

52.688

52.690

20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 65.00 70.00

Del

ay (µ

s)

MKI8-D_dn Measured Temperature (˚C)

MKI.UA87.IPOC.DB2:T_DELAY (October 2011)

The above shows a fairly linear correlation between magnet temperature, made during SoftStarts in Oct. 2011, and rise-time up to 60°C (for MKI8D_dn). The temperature dependence of the magnet capacitors (~−800ppm/°C), e.g. assuming the ground plate is at ambient temperature, is probably responsible for the initial slope (−0.04ns/°C for MKI8D_dn). The slope of the reduction of the rise-time increases above 60°C measured for MKI8D_dn, indicating some of the ferrite yoke is at the Curie temperature.

The correlation between magnet temperature, made during SoftStarts in Oct. 2011, and absolute delay is noisy – probably due to thyratron jitter. The delay measurement should be improved, following the winter TS, by finding the delay w.r.t. thyratron cathode current.

y = -1.325E-05x + 7.069E-01R² = 1.501E-02

y = -7.324E-05x + 7.041E-01R² = 7.792E-01

y = -2.065E-05x + 6.970E-01R² = 3.514E-01

y = -3.563E-05x + 7.004E-01R² = 8.375E-01

y = -2.828E-04x + 7.153E-01R² = 6.809E-01

0.695

0.696

0.697

0.698

0.699

0.7

0.701

0.702

0.703

0.704

0.705

0.706

0.707

0.708

0.709

20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00 65.00 70.00

Rise

Tim

e (µ

s)

MKI8 Measured Temperature (˚C)

MKI.UA87.IPOC.?B2:T_RISETIME (October 2011)

MKI.UA87.IPOC.AB2:T_RISETIME

MKI.UA87.IPOC.BB2:T_RISETIME

MKI.UA87.IPOC.CB2:T_RISETIME

MKI.UA87.IPOC.DB2:T_RISETIME

Δ3ns Δ4% for Lc, & accelerating?

23 November 2011 6M.J. Barnes

Initial permeability of CMD5005 increases to a max. at ~100°C, then starts to rapidly reduce.

M.J. Barnes 7

MKI8: Correlation Between Measured Magnet Temperatures

y = 0.6415x + 8.7734y = 0.3498x + 12.651y = 0.4692x + 10.139y = 0.4304x + 13.182

202224262830323436384042444648505254

20 25 30 35 40 45 50 55 60 65 70

MKI

8_M

agne

t (˚C

)

MKI8D_Mag-Down (˚C)

MKI.B5R8.B2:TEMP_MAGNET_DOWNMKI.A5R8.B2:TEMP_MAGNET_UPMKI.C5R8.B2:TEMP_MAGNET_UPMKI.D5R8.B2:TEMP_MAGNET_DOWN

The above magnet temperature data, made during SoftStarts in October 2011, shows linear correlation between the measured magnet temperatures....

23 November 2011

M.J. Barnes 8

Beam Impedance Reduction Ferrites Purpose of BIRF is to “encourage” image current of beam to

flow through screen conductors. Rather than through the magnet tank.

Ideally image current of beam should flow through metallization/capacitive coupling/screen conductors/SS tube... Thus, ideally, there is no net field, due to beam current, which can couple into BIRFs.

In reality, BIRFs get hot (due to beam coupling) so there is field coupling into the BIRF’s, i.e. not all the beam image current is flowing in the ceramic tube metallization or SS tube.

BIRF heating may be partially attributable to non-perfect RF fingers – especially after bake-out. Note: ~50% increase in power deposition after bake-out!!

ALSO BIRF heating is probably also due to presence of capacitive coupling at one end…. ~200 pF @ 10 MHz ~80 Ω (Note: 1 MHz ~800 Ω) ~3 µH (each BIRF) @ 10 MHz ~400 Ω for 2 BIRFs

Assume ~3 µH with tank as return @ 10 MHz ~200 ΩHence BIRF probably does not help at frequencies << 10MHz….

23 November 2011

Beam

Ideally beam image current flows, homogeneously within inside radius of ferrite.

M.J. Barnes 9

Screen Conductors Ceramic has 24 slots for screen

conductors: only 15 installed to decrease probability of HV breakdown. 15 conductors results in ~3x power beam induced power deposition, in the ferrite yoke, in comparison with 24 screen conductors.

Adding spheres to end of screen conductors will reduce electric field strength and, hopefully, allow 24 conductors to be installed.

Alternative idea for beam screen (beam impedance to be investigated by Hugo): connect only 2 of 24 screen conductors to ground, and capacitively couple others to ground reduces peak voltages by ~2……….

BUT: low frequency impedance will increase…..23 November 2011

Connect to beam-pipe ground

+16kV/-9kV

+1kV/-2kV

+27kV/-17kV

+23kV/-14kV

+11kV/-6kV

24 conductors capacitively coupled to beam-pipe ground

Connect to beam-pipe ground

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+7kV/-13kV

+4kV/-9kV

+6kV/-3kV

+16kV/-10kV

24 conductors capacitively coupled to beam-pipe ground

22 conductors capacitively coupled to beam-pipe ground

M.J. Barnes 10

Conclusions Mag_Up would be expected to measure a higher temperature than

Mag_Dn, because of PT100 position, but this is not always the case…. Tube_Up temperature > Tube_Dn temperature. Measured temperature of MKI8D_Dn reached 68˚C during October. The

slope of the reduction of the rise-time increases above 60°C, measured for MKI8D_Dn, indicating some of the ferrite yoke is above the Curie temperature. Other MKI8’s do not yet show evidence of yoke being at the Curie temperature.

One BIRF measured temperature reached 102°C during October. BIRF (and a portion of ferrite yoke) heating is probably due to both non-perfect RF fingers (especially after bake-out) and the impedance of the capacitive coupling at frequencies << 10MHz.

Alternative beam screen configurations, which should allow 24 (c.f. 15 screen conductors) to be installed, are under consideration. The extra 9 screen conductors would reduce the expected beam induced power deposition by a factor of ~3.

23 November 2011

M.J. Barnes 11

Spare Slides …….Status of Installed MKI Magnets

23 November 2011

Status des aimants MKI Date: 10/12/2010

Installés P2 (sens d'injection)

No aimants Diam. Tube

céramiqueNbr stripes

Nbr.dampingresistor

Nbr. essais Labo

Nbr. Pls Cond. Labo

Nbr. Pls Cond.

LHC

Nbr. Pls Opération

Nbr. Totalde pulses

Nbr. Cls Cond. Labo

Nbr. Cls Cond.

LHC

Nbr. Cls Opération

Dissipationen

W/mRemarques

9 53 15 2 6 537503 537503 40 89 (4) D MKI44. graded conductors4 53 15 2 3 207052 15617 222669 0 0 76 (2) C MKI43. graded conductors

10 53 15 2 97 B mki46a. Graded conductors8 53 15 2 2 150954 15617 166571 0 0 60 A MKI37. Staggered conductors

Installés P8 (sens d'injection)

No aimants Diam. Tube

céramiqueNbr stripes

Nbr.dampingresistor

Nbr. essais Labo

Nbr. Pls Cond. Labo

Nbr. Pls Cond.

LHC

Nbr. Pls Opération

Nbr. Totalde pulses

Nbr. Cls Cond. Labo

Nbr. Cls Cond.

LHC

Nbr. Cls Opération

Dissipationen

W/mRemarques

6 51 15 1(masse) 1 164294 114240 278534 6 0 D

2 51 15 1(masse) 2 223244 114240 337484 6 0 C3 51 15 2 3 105820 114240 220060 1 1 B1 51 24 (9 raccourcis) 2 4 488689 114240 602929 3 0 88 A

BEA

MBE

AM

M.J. Barnes23 November 2011 12

Connect to beam-pipe ground

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+16kV/-10kV

+7kV/-13kV

+4kV/-9kV

+6kV/-3kV

+16kV/-10kV

24 conductors capacitively coupled to beam-pipe ground

22 conductors capacitively coupled to beam-pipe ground

Connect to beam-pipe ground

+16kV/-9kV

+1kV/-2kV

+27kV/-17kV

+23kV/-14kV

+11kV/-6kV

24 conductors capacitively coupled to beam-pipe ground