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EMC PROGRAM ON THE ACCELERATOR RINGS

Basic concept of grounding in the accelerator ring Cabling and grounding in the RCS Cabling and grounding in the main ring

Cabling and grounding of injection/extraction pulse power system Grounding and shielding of RF system Ceramic breaks of the main ring Noise immunity reinforcement plan of beam monitors

K. Okamura (KEK), Y. Watanabe (JAEA)

TOPICS

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BASIC CONCEPT OF GROUNDING IN THEACCELARATOR RING

Vacuum chambers including monitors are grounded in the tunnel.Beam pipes passing through magnets are isolated from themagnet.RF, kicker, collimator, and SEP are grounded in the tunnel.

BM, QM, SM, and StM are grounded in the power supply building.Ion pumps are isolated from beam pipes.Ceramic breaks are provided at upstream point of BMs.In RCS, ceramic breaks are provided with every magnet using

ceramic duct.

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CABLING AND GROUNDING IN THE

RCS All power cable is twisted and shielded. Cable shielding is grounded in one-sided. Power supply housing is insulated from floor and water pipe. Main circuit is only grounded in neutral point.

Policy

Switchgear Transformer Power supply

Chokes Capacitor banks

Earth point(Utility) Earth point(Magnet)

MagnetsNeutral point

ToChokes

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CERAMIC BREAKS RCS-

Dipole magnet

Ceramics duct

Epoxy resin

capacitor

Titanium sleeve

Ceramics vacuum duct installed in dipole magnet

Ceramics duct is installed in every dipole and quadrupole magnets.

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CABLING AND GROUNDING POLICY IN

THE MAIN RING Main circuits are fed by cables with shields.

Magnets are not grounded in the tunnel but at power

supply side. Grounding cables are installed separately with each

magnet family B, 11 Q-families, 3 S-families) .

Grounding cables are also installed between atransformer and a power supply.

Grounding of cable racks is under consideration.

TRANS YARD BUILDING

TUNNEL

P

N

0

0

Potential of the Power Line

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Q**,S ++

Earth Cable are separately fedby each magnet family and

has open end symmetrically. QFP,SDB

**:FN,DN,FX,DX

FR,FS,FT,DR,DS,DT

++:FA,DA

GROUNDING CONNECTION OF QUADRUPOLE AND SEXTUPOLE MAGNETS

Potential 0 Potential 0

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Grounding Cable are separatelyfed by each power supplybuilding

Building D3

Building D1

BM1BM

BM3

BM4

BM5

BM6

P

P

P

P

P

P NN

N

N

N

N

Building D2

GROUNDING CONNECTION OF BENDING MAGNETS

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PULSE MAGNET POWER SUPPLY FOR INJECTION

AND EXTRACTION SYSTEM

Coils are not grounded in the tunnel but grounded inpower supply buildings through power cables.

Magnetic core, vacuum duct, and frame are groundedboth in the tunnel and buildings.

Each grounding points are connected by cables.

400mm2 400mm2

Vacuum

Chamber

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PULSE MAGNET POWER SUPPLY FOR A KICKER

SYSTEM

Outer conductor of a coaxial cable is connected toframes at both end.

Magnetic core, vacuum chamber, and frame aregrounded in a tunnel, also grounded in a buildingthrough the coaxial cable.

HV

PS

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GROUNDING AND SHIELDING OF RF SYSTEM

In general, grounding is designed so that drive current must directlyreturn to each corresponding power supply.

1.2MW anode power supplies are switched mode power supply w/IGBT inverters.Tri-axial cable for tube anode supply is used for shielding highfrequency EMI noise.

Single point grounding is performed.However, cavity /amplifier chassis are grounded w/ resistor forsafety

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CERAMIC BREAKS OF THE MAIN RING

ARC section (#1,#2, #3): Breaks at an upper stream point of each bending magnet

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Noise immunity reinforcement plan of beam monitors

Grounding is done in the tunnel or the control room(power supply buildings).

(possible to ground at the both ends, optionally)

Beam pipe will be grounded in the tunnel via each BPM,

to prevent from charging up.

Use high shielding efficiency cables

Proper use of noise-shielded transformers.

Use common mode chokes

high shielding efficienc cables

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high shielding efficiency cables Screening effectiveness depends on the construction of outer conductor:

Semi-rigid, corrugated metal > longitudinal metale.g. aluminium) foil > braid wire

other factors to be considered

radiation hardness, cost

Example: induced noise on the cable under noisy environment

with a switching power supply

outer conductor RG58 c/u: copper braid wire ( 5 m)S04272B: longitudinal metal foil ( 4 m )

from the HUBER+SUHNER cable catalgue

rigid! flexible

10MHzDC

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ch.1&2

ch.3&4

Beam position monitors (BPMs)

noise cut trans.

AC100V

Connection tothe GNDdepends on

noise observation.

The shielding of coaxial cablesare connected to the beam pipevia connectors.

Grounding in the tunnel.

High shielding efficiency coaxial cables

surrounded by another shield.

option: commom mode choke coil.

Tunnel

Control room(power supply

building) Grounding in the control room

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SUMMARY

EMC program of the accelerator ring is mainly focused on grounding.

Two golden rules of grounding are one point grounding and safety.

Power supply, beam pipes, vacuum pumps are grounded separately.

Grounding of cable rack is under consideration.

As to beam monitors, high efficiency shielding cables are selected