impedance of the totem roman pots nicola minafra, benoit salvant, nicolò biancacci, …

Impedance of the TOTEM Roman Pots

Nicola Minafra, Benoit Salvant, Nicolò Biancacci, …

2 Impedance of the TOTEM RPs - Nicola Minafra

The RP system

23/03/2015


The RP system

23/03/2015

Vertical RP

Cylindrical RPHorizontal RP

Shielded RP

4 X

2 X 1 X

2 X


Wakefield simulations using CST

23/03/2015

Real part of the longitudinal impedance for the old horizontal RP at various distances d (mm) from the beam


Wire and probe tests

23/03/2015

Sim

ula

tion

sM

easu

rem

en

ts

Cylindrical RP Shielded RP

TOTEM NOTE: RF Measurements of the New TOTEM Roman PotOnly geometrical contribution!


The RP system

(High intensity)

D(mm)

USED?

OLD (PAIR) 6.6 YES*

SHIELDED 3.0 YES

SHIELDED 2.1 YES

OLD (PAIR) 6.2 YES*

OLD (PAIR) 6.1 GARAGE

OLD 1.9 GARAGE

CYLINDRICAL 1.9 YES

OLD 1.6 GARAGE


D(mm)

USED?

OLD (PAIR) 6.5 YES*

SHIELDED 3.1 YES

SHIELDED 2.2 YES

OLD (PAIR) 5.9 YES*


OLD 2.0 GARAGE

CYLINDRICAL 2.0 YES

OLD 1.7 GARAGE


Beam 1 Beam 2

23/03/2015

* Vertical RP can be extracted in case of problems


The RP system

(Low intensity)

D(mm)

USED?


SHIELDED 7.9 GARAGE

SHIELDED 6.5 YES

OLD (PAIR) 6.4 YES

OLD (PAIR) 6.6 YES

OLD 6.1 YES

CYLINDRICAL 6.0 GARAGE

OLD 5.4 YES

OLD (PAIR) 7.4 YES

D(mm)

USED?


SHIELDED 7.8 GARAGE

SHIELDED 6.4 YES

OLD (PAIR) 6.6 YES

OLD (PAIR) 6.8 YES

OLD 6.0 YES

CYLINDRICAL 5.9 GARAGE

OLD 5.3 YES

OLD (PAIR) 7.5 YES

Beam 1 Beam 2

23/03/2015


Low frequency longitudinal impedance

𝑍∥𝑙𝑓

𝑛≡ lim

𝑓 →0𝑓 𝑟𝑒𝑣

𝑑ℑ [𝑍∥ ]𝑑𝑓

11425 (𝐻𝑧 )×160 ( Ω𝐺𝐻𝑧 )

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.160

4

8

12

16

20f(x) = 103.177349381558 x² + 148.961278332917 xf(x) = 160.132651514926 x

Frequency (GHz)

ℑ[

∥] @

1.6

mm

𝑍

difference

23/03/2015



23/03/2015

ℑ[𝑍 ∥

]

Low frequency longitudinal impedance is a conservative estimation of the effective longitudinal impedance

Horizontal Old RP 5.4 mm form the beam

,



23/03/2015

, Low frequency longitudinal impedance is a conservative estimation of the effective longitudinal impedance

Cylindrical RP 1.9 mm form the beam

ℑ[𝑍 ∥

]


0 5 10 15 20 25 30 35 400

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Distance from the beam (mm)

∥𝑍/ (

mΩ

)𝑛

Old RP horizontal,

D (mm)

5.3 115.3 1.40

5.4 115.2 1.39

6.0 111.1 1.35

6.1 110.6 1.34

40 79.1 0.42

23/03/2015


Old RP vertical,

D (mm)

5.9 138.7 1.56

6.2 137.5 1.55

6.4 136.6 1.54

6.5 136.2 1.53

6.6 135.8 1.53

6.8 134.8 1.52

7.4 132.4 1.49

7.5 132.0 1.48

40 141.5 0.640 5 10 15 20 25 30 35 40

0

0.4

0.8

1.2

1.6

2


∥𝑍/ (

mΩ

)𝑛

23/03/2015


0 10 20 30 400

0.2

0.4

0.6

0.8

1

1.2

1.4


∥𝑍/ (

mΩ

)𝑛

Shielded RP,

D (mm)

2.1 109.15 1.23

2.2 108.27 1.22

3.0 101.85 1.15

3.1 101.11 1.14

6.4 81.43 0.92

6.5 80.95 0.91

40 29.27 0.33

23/03/2015


Cylindrical RP,

D (mm)

1.9 102 1.15

2.0 101 1.14

40 17 0.19

0 5 10 15 20 25 30 35 400

0.2

0.4

0.6

0.8

1

1.2

1.4

Distance form the beam (mm)

∥𝑍/ (

mΩ

)𝑛

23/03/2015


Low frequency transverse impedance

𝑍❑𝐷

⊥𝑙 𝑓 =

𝛽⊥⟨ 𝛽⊥ ⟩

𝑍❑𝐷

⊥𝑙 𝑓=

𝛽⊥⟨ 𝛽⊥ ⟩

lim𝑓→ 0

𝑑 ℑ [𝑍⊥]𝑑𝑥

𝑍⊥𝑙 𝑓 (𝑥 )≈ 𝑍❑

𝐷⊥ 𝑥+ 𝑍❑

𝑄⊥𝑥+⋯

23/03/2015

Moving the particle beam,integration path always in the centre

𝑍❑𝑄

⊥𝑙 𝑓=

𝛽⊥

⟨ 𝛽⊥ ⟩𝑍❑

𝑄⊥𝑙 𝑓=

𝛽⊥

⟨ 𝛽⊥ ⟩lim𝑓→ 0

𝑑 ℑ [𝑍⊥]𝑑𝑥

Moving the integration path,beam always in the centre

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1

-1.8

-1.6

-1.4

-1.2

-1

-0.8

-0.6

-0.4

-0.2

0f(x) = − 19.5358333333333 x − 0.013495f(x) = − 21.8883333333333 x − 0.0535833333333333f(x) = − 25.2033333333333 x − 0.0148333333333334f(x) = − 26.2066666666667 x + 0.00100000000000011

5.9 mmLinear (5.9 mm)6.2 mmLinear (6.2 mm)6.4 mm6.5 mmLinear (6.5 mm)7.4 mmLinear (7.4 mm)

Beam displacement (mm)

ℑ[

Y]

(Ω)

𝑍


Old RP horizontal,

23/03/2015

D (mm)

40284.77 /

7321.63 /

672 1 1.5 0.5 8 0.5 3.9 0.2

40263.44 /

7314.98 /

672 1 1.5 0.5 7 0.3 3.6 0.1

40261.88 /

7323.53 /

672 1 1.5 0.5 7 0.5 3.6 0.2

40238.20 /

7316.46 /

672 1 1.5 0.5 7 0.4 3.3 0.1

𝛽∗=0.8𝑚

D (mm)

5.3640.15 /

73309.70 /

678 8 10 7 88 42 70 32

5.4758.39 /

73320.82 /

678 8 9 7 93 43 83 34

6.0673.18 /

73395.82 /

677 7 9 5 83 53 64 30

6.1797.72 /

73410.74 /

677 7 9 5 98 55 76 31

𝛽∗=90𝑚


Old RP vertical,

D (mm)

5.9 273.3 / 7327.93 /

6726 10 10 11 97 4 37 5

6.2295.00 /

7325.9 / 67 25 9 9 11 101 3 36 4

6.5329.85 /

7357.69 /

6722 9 9 11 99 8 41 9

6.6345.16 /

7355.44 /

6722 9 9 10 104 7 43 8

40286.96 /

7322.49 /

673 1 2 2 12 0.5 4 0.5

40261.36 /

7314.51 /

673 1 2 2 11 0.5 4 0.5

40264.32 /

7324.42 /

673 1 2 2 11 0.5 4 0.5

40235.90 /

7315.94 /

673 1 2 2 10 0.5 3 0.5

𝛽∗=0.8𝑚

23/03/2015


Old RP vertical,

D (mm)

6.4588.49 /

73456.29 /

6723 9 10 11 185 68 72 75

6.6618.97 /

73439.42 /

6722 9 9 11 186 59 76 72

6.6628.84 /

73420.38 /

6722 9 9 10 189 56 78 63

6.8661.26 /

73405.05 /

6721 9 9 10 190 54 81 60

7.4770.82 /

73312.42 /

6719 8 8 9 200 37 84 42

7.5810.80 /

73301.64 /

6718 8 8 9 200 36 89 40

40378.55 /

73698.84 /

673 1 2 2 15 21 5 21

40397.68 /

73671.46 /

673 1 2 2 16 20 5 20

𝛽∗=90𝑚

23/03/2015


Cylindrical RP,

23/03/2015

D (mm)

1.9281.69 /

7320.48 /

6726 27 24 100 7 105

2.0258.45 /

7322.32 /

6724 25 23 85 8 88

𝛽∗=0.8𝑚

D (mm)

40656.27 /

73397.34 /

671 1 9 6

40690.15 /

73382.99 /

671 1 9 6

𝛽∗=90𝑚


23/03/2015

𝑃 𝑙𝑜𝑠𝑠=2 𝐼2∑𝑝=0

∞

𝑃 .𝑆 . (𝑝𝑀 ′ 𝑓 𝑟𝑒𝑣 )ℜ [𝑍¿¿ 𝑙𝑜𝑛𝑔 (𝑝𝑀 ′ 𝑓 𝑟𝑒𝑣 )]¿

Beam current:

LHC Power Spectrum

LHC revolution frequency

Number of buckets: 3564

The computation has been done using a flat top Power Spectrum with a bunch spacing of 25 ns.

Impedance contribution is only geometrical.

Power loss: heating


0 5 10 15 20 25 30 35 400

10

20

30

40

50

60

25 ns, 3564 bunches, 1.6 10^11 p per bunch: beam current = 1 A

25 ns, 3564 bunches, 10^11 p per bunch: beam current = 0.65 A



He

ati

ng

(W

)

Old RP horizontal, heating

23/03/2015


0 5 10 15 20 25 30 35 400

10

20

30

40

50

60




Distance from beam (mm)

He

ati

ng

(W

)

Old RP vertical, heating

23/03/2015


0 5 10 15 20 25 30 35 400

2

4

6

8

10

12

14





He

ati

ng

(W

)

Cylindrical RP, heating

23/03/2015


Total D

(mm)

OLD (PAIR)

6.61.53

(0.64)< 0.1

0.2(< 0.1)

SHIELDED

3.0 1.15

SHIELDED

2.1 1.23

OLD (PAIR)

6.21.55

(0.64)< 0.1

0.2(< 0.1)

OLD (PAIR)

40 0.64 < 0.1 < 0.1

OLD 40 0.42 < 0.1 < 0.1

CYLINDRICAL

1.9 1.15 << 0.1 0.1

OLD 40 0.42 < 0.1 < 0.1

OLD (PAIR)

40 0.64 < 0.1 < 0.1

TOTAL 8.7(6.9)

D (mm)

OLD (PAIR)

6.51.53

(0.64)<0.1

0.2(< 0.1)

SHIELDED

3.1 1.14

SHIELDED

2.2 1.22

OLD (PAIR)

5.91.56

(0.64)< 0.1

0.2(< 0.1)

OLD (PAIR)

40 0.64 < 0.1 < 0.1

OLD 40 0.42 < 0.1 < 0.1

CYLINDRICAL

2.0 1.14 << 0.1 0.1

OLD 40 0.42 < 0.1 < 0.1

OLD (PAIR)

40 0.64 <0.1 <0.1

TOTAL 8.7(6.9)

23/03/2015


Total D

(mm)

OLD (PAIR)

40 0.64 << 0.1 << 0.1

SHIELDED

40 0.33

SHIELDED

6.5 0.91

OLD (PAIR)

6.4 1.54 0.2 < 0.1

OLD (PAIR)

6.6 1.53 0.2 < 0.1

OLD 6.1 1.34 < 0.1 0.1

CYLINDRICAL

40 0.19 << 0.1 << 0.1

OLD 5.4 1.39 < 0.1 0.1

OLD (PAIR)

7.4 1.49 0.2 < 0.1

TOTAL 9.4

D (mm)

OLD (PAIR)

40 0.64 << 0.1 << 0.1

SHIELDED

40 0.33

SHIELDED

6.4 0.92

OLD (PAIR)

6.6 1.53 0.2 < 0.1

OLD (PAIR)

6.8 1.52 0.2 < 0.1

OLD 6.0 1.35 < 0.1 0.1

CYLINDRICAL

40 0.19 << 0.1 << 0.1

OLD 5.3 1.39 < 0.1 0.1

OLD (PAIR)

7.5 1.48 0.2 < 0.1

TOTAL 9.4

23/03/2015


Conclusion

RP at maximum insertion

8.7 (6.9)

RP at maximum insertion

9.4

All RP in GARAGE

4.2

All RP in GARAGE

(before LS1)4.2

23/03/2015

• New cylindrical RP and 2 shielded RP per beam

• New ferrites: new material and 1000°C bake-out

• improved after LS1 for all RP in garage position

( with 1 RP more! )

• Less than 2x higher when RP inserted for high intensity runs, with respect to garage position

• Negligible dipolar and quadrupolar and

impedance of the totem roman pots nicola minafra, benoit salvant, nicolò biancacci, …

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