Vacuum pressures at ir
This presentation is the property of its rightful owner.
Sponsored Links
1 / 21

Vacuum Pressures at IR PowerPoint PPT Presentation


  • 125 Views
  • Uploaded on
  • Presentation posted in: General

Vacuum Pressures at IR. Y.Suetsugu KEKB Vac. Group. Contents. Outline of Vacuum System at IR Behavior of Pressures Remedies for Heating of Vacuum Components. Vacuum System at IR.

Download Presentation

Vacuum Pressures at IR

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Vacuum pressures at ir

Vacuum Pressures at IR

Y.Suetsugu

KEKB Vac. Group

Contents

  • Outline of Vacuum System at IR

  • Behavior of Pressures

  • Remedies for Heating of Vacuum Components


Vacuum system at ir

Vacuum System at IR

  • Here IR (Interaction region) means the straight section in ±~100 m from IP (Interaction Point), especially upstream side of each ring.

  • Material of beam duct: OFC (Oxygen Free Copper) for most part (both rings). Aluminum alloy for complicated chamber just near to IP.

[Aluminum Alloy]

[OFC]


Vacuum system at ir1

Vacuum System at IR

  • Vacuum pump: Main pump = NEG (st707) : almost every 1 m (0.2 m3/s), Auxiliary pump = Ion pumps : almost every 10 m (0.2 m3/s). In average, about 0.7 m3/s/m just after an activation of NEG.

NEG cartridge

(arc section)

NEG module

(just near to IP)


Vacuum system at ir2

Vacuum System at IR

  • Vacuum gauge = CCG (Cold Cathode Gauge) just above ion pumps (every ~10 m). A small dipole magnet (permanent magnet) is attached at the neck of gauge port to eliminate photoelectron effect.

Without Manget

CCG

~100 G


Vacuum system at ir3

Vacuum System at IR

  • Location of Gauges and Pumps near to IP

HER

LER

D01_H02

D02_H23

IP

D01_H02A

D01_H01A

D02_H23A

(D02_H24)

[Inside of BELLE Solenoid]

Integrated NEG

Integrated NEG

0

10 m

5 m


Vacuum system at ir4

Vacuum System at IR

  • HER Upstream Side (straight section, ~100 m)

  • Straight : No bending magnet

  • Gauges: every ~10 m

D01_H01A

D01_H03

D01_H02A

D01_H04

D01_H05

IP

GV

GV

D01_H06

D01_H7

D01_H8

GV

BS

D01_H10

D01_H09

D01_H11

HER


Vacuum system at ir5

Vacuum System at IR

  • LER Upstream Side (straight section, ~100 m)

  • Local correction region: 13 bending magnets

  • Gauges: every ~10 m

LER

D02_L16

D02_L17

GV

BS

GV

D02_L19

D02_L20

D02_L18

IP

GV

D02_L21

D02_L22

D02_H23A

D02_L23

D02_L24


Behavior of pressure

Behavior of Pressure

  • HER_1

Three days

including several

beam Injections.

D01_H04

D01_H03

D01_H02A

D01_H01A

IP

D01_H06

D01_H7

D01_H8

2x10-7 Pa

Heat Source

= Gate Valve

P

Big BG Source

0

0

1.4 A

Ib


Behavior of pressure1

Behavior of Pressure

  • HER_2

Three days

including several

beam injections.

Gate Valve

D01_H7

D01_H8

Gate Valve

D01_H06

D01_H09

Heat Source

= HOM Absorber,

Taper

D01_H10

D01_H11

Heat Source

= Stopper (~ Gate Valve)


Behavior of pressure2

Behavior of Pressure

Three days

including several

beam aborts.

  • LER_1

? (NEG?)

D02_L20

D02_L18

D02_L19

IP

D02_L21

D02_H23A

D02_L23

Heat Source

= Gate Valve

D02_L22

D02_L24

3x10-7 Pa

P

Heating +NEG?

Multipactoring?

0

0

2.0 A

Ib


Behavior of pressure3

Behavior of Pressure

Three days

including several

beam aborts.

  • LER_2

Heat Source

= Taper

Heat Source

= Stopper

D02_L16

D02_L17

D02_L15

Gate Valve

Gate Valve

D02_L19

D02_L20

D02_L18

? (NEG?)


Present status

Present Status

  • The pressures near to IP is <1x10-7 Pa for HER and ~2x10-7 Pa for LER at the maximum operation current.

  • The pressures at upstream side of IP (IR) is almost less than 1x10-7 Pa,but affected by the heating of components, such as gate valves, stoppers, HOM absorbers and NEG(?).

  • The same harmful effect by heating can be seen widely in arc sections too. A major problem for further improvement of pressure.


Remedies to heating

Remedies to heating

  • Main reason of the heating is HOM.

  • Heating of Gate Valves, Stoppers and Bellows

    • Finger-type RF shield is not enough for high current

    • TE mode can easily coupled to modes outside

  • Tentative measure = Cooling from outside

[Gate Valve]

symptomatic therapy

[Bellows]


Remedies to heating1

Remedies to heating

  • Future (more essential) measure

    • Proposal of a New RF-shield structure

    • Comb-type RF-shield

  • 6 circular-type and 1 race-track-type has been installed in LER, and showed good results.

  • Application to gate valves are now planed and a test model will be installed in the ring this winter.


Remedies to heating2

Remedies to heating

  • Heating of NEG

    • Gas desorption from heated NEG had been observed near collimators.

  • HOM (TE-mode) intruded through a grid into pump port.

  • Tentative measure = use a special gasket

f = 6 mm

t = 2 mm

Cu

Lead to heating of other components

  • HOM absorber were installed finally.


Remedies to heating3

Remedies to heating

  • Heating by other HOM sources, such as collimators or tapers.

  • Install HOM absorber chamber

    • Example installed near collimators

    • HOM absorber = SiC

SiC

Slot

Wing

SiC

Beam Chamber

Require Space ! How about IR?


Summary

Summary

  • The pressures at upstream side of IP is almost less than 1x10-7 Pa, but also affected by the heating of components, such as gate valves, stoppers, tapers, NEG and HOM absorbers.

  • The problem had been solved accordingly so far. But, essential (drastic) remedies, such as employing new RF-shield or installing HOM absorbers, will be required for future high current operation.

  • Improvement of pumping speeds and cooling capacity are of course important.


References

References


Present status1

Present Status

  • Typical Run(11/09/2004)

Beam Current

1.2A x 1.6 A

Lifetime

230, 180 min

Ave. Pressure

10-7 Pa

Luminosity

~1.1x1034cm-2/s

Beam currents are usually limited by any problems in vacuum components


Present status2

Present Status

(If S = 0.3 m3/s/m)

  • Vacuum Aging (arc section, -2004/10/31)

    • DP/DI : 1x10-7 Pa/A

    • Photo-desorption coefficient,h : ~ 3x10-7 mole./photon

    • Effect of photoelectrons were eliminated by magnets.

    • HER seems to be effected by heating of components.

[LER]

[HER]

DP/DI

DP/DI

Max. I

Max. I

[Pa/mA]

[Pa/mA]

PM

PM

[mA]

[mA]

(Corrected)

[PM]:Set permanent magnets to every gauge port


Present status3

Present Status

Just near to GV!

  • Vacuum pressures in HER (~300 gauges)

(ARES)

(ARES)

(SCC)

(SCC)


  • Login