Differential Pumping with an Insert of a Narrow Aperture in the - - PowerPoint PPT Presentation

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Differential Pumping with an Insert of a Narrow Aperture in the - - PowerPoint PPT Presentation

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Differential Pumping with an Insert of a Narrow Aperture in the PIP2IT MBET Alex Chen on behalf of the PIP2IT task force: Outline Motivation and Layout MEBT of Absorber to HWR(DP section) Function Requirement Design of DPI

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SLIDE 1

Alex Chen on behalf of the PIP2IT task force:

Differential Pumping with an Insert of a Narrow Aperture in the PIP2IT MBET

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SLIDE 2
  • Motivation and Layout MEBT of Absorber to HWR(DP

section)

  • Function Requirement
  • Design of DPI

▪ Mechanical solution ▪ Vacuum solution ▪ Electrical solution ▪ Thermal solution

  • DPI-FV Vacuum test setup
  • Vacuum Test results
  • Summary

Outline

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

2

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SLIDE 3

DP Layout (Absorber to HWR)

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

3

Vacuum Space Length: 3377mm

1) Gas(H2) Flux from Absorber: 1E-5mbar.l/s 2) Uniform

  • utgassing rate:

1e-10 starts, 1e-11 ultimate

100 l/s, 100 l/s, 400 100 l/s, 400 FV DPI

The primary purpose of differential pumping section is to minimize the gas flux and particulates from MEBT to HWR during operation or vacuum failure in MEBT

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SLIDE 4

FRS of DPI (ED0004472)

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

4 Parameters Value Units Position alignment of the DPI tube with respect to beam line axis ≤ 0.5 mm Angular alignment with respect to beam line axis*1 ≤ 2 mrad Cooling Natural air convection Maximum average power 25 W Maximum pulse energy deposition*2 0.4 J Electrical isolation with respect to ground 300 V Maximum current to report (CW/tuning) 20 /200 µA Current reading accuracy *3 (CW/tuning) ≤ 1 / 10 µA Accident detection: minimum trip level*4 Averaged over 5 µs 100 µA Averaged over 1/60 s =16.6 ms 5 µA

  • DPI Requirments

Parameters Valu e Unit s Ion type H- Beam energy 2.1 MeV Operation mode Nominal beam size at DPI (6σ), X/Y 8/8 mm Maximum beam current, CW 10 mA Tuning mode Pulse repetition rate Hz 20 Pulse length µs 20 Maximum pulse beam current 10 mA

  • Relevant beam parameters

Parameters Value Units Material of beam – exposed portion of DPI tube copper Minimum diameter of DPI tube 10 mm Length of DPI tube 200 mm Ion pump speed 100 l/s

  • Recommended DPI Parameters
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SLIDE 5

Mechanical

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

5

  • Insertion length with Ion Pump: 435mm
  • Positioning

▪ DPI is supported common girder with adjustment ▪ Position of aperture is determined by aligning cooling disc OD

Position alignment of the DPI tube with respect to beam line axis ≤ 0.5 mm Angular alignment with respect to beam line axis*1 ≤ 2 mrad

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SLIDE 6

Vacuum considerations

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

6

  • Absorber is high outgassing of Hydrogen ( at level of 10-4

torr.l/s) and loose particles

  • Uniform outgassing rate applied inner surfaces of SS and

Copper

  • Pump distribution studied
  • Distance of DPI-IP studied
  • Pressure ratio of before/after DPI calculated
  • Detail Results show in ppt of Molflow+ Simulation
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SLIDE 7

Design of DPI

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

7

Copper Tube 10mm(ID),200mm(Lon g) SS tube 1.5”(OD)

  • Al. cooling

Disc Ceramic Breaker (3kV) Ion Pump (100 l/s) Beam

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SLIDE 8

Pressure Profile by MolFlow Simulation

(Absorber to HWR, 1E-5 mbar.l/s H2,)

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

8

1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Pressure ( mBar) Distance From DS of Absorber(m)

PXIE Vacuum From Absober to HWR

q=1e-11,p=100,100,100 q=1e-10,p=100,100,100 q=1e-10,p=100,400,100 q=1e-10,p=0,100,400 q=1e-10,p=100,100,400

DP Ratio 33,17,21,18,2

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SLIDE 9

Thermal solution

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

9

Analyses were done on 1)material choices of inner tube, 2)heating distributions, 3)relative longitudinal positions

  • Beam-Copper-SS-Alu-Air
  • Worst case, 25w of heat

at front face

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SLIDE 10

Setup in final locations

10

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

FV DPI S2 S1 GV

RFQ HWR

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SLIDE 11

Setup in Current configuration

11

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

FV DPI S2 S1 L1 L2 GV WRG FV CTL PLC5 WRG WRG

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SLIDE 12

1st Test on MEBT DPI-FV

12

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

M72WRP M61VSO M71S2P M63WRP M63DIP M11PIP M81VFC

LD PG Leaker Volume=0.3 liter

M72PIO M92WRP

1.

V1=36.5 liters(M61VSO-FV)

2.

V2=95.1 liters(POST FV)

3.

Permeation rate from Scanner O-Ring is about 6E- 7 torr.l/s

M52WRP

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SLIDE 13

Setup of Test

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

13

N2 Reservoir (0.33 Liter) Post FV Volume (2.79 liter) FV CC Gauge RGA Ion Pump (45 l/s) Pirani Gauge With current 45 l/s, 3E-9 torr has been achieved without baking

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SLIDE 14

Differential Pumping Effect

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

14

With current setup

  • f DPI and IPs,

DPus/DPds =188 6.6E-6 7.6E-7 1.5E-8 4.6E-8 Pressure rise at US of DPI Pressure rise DS of DPI

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SLIDE 15

Vacuum Gauge reading on Beamline (Leak

From Upstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

15

DPI significantly reduce gas flux

3.7E-1 1.9E-2 4.5E-5 6.0E-5

Pressure rise at US of DPI Pressure rise at DS of DPI

forced

  • pen

1.7 torr 52 torr IPs stay IPs strip

  • ff
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SLIDE 16

Vacuum Gauge Reading in Small Volume (Leak From Upstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

16

1.7E-7 with

Leaker at 1.7 Torr

1.9E-7 with

leaker at 52 Torr

7.6E-8

When open FV

~2.3E-8 ~1.7E-8 Aug 23, 2-18

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SLIDE 17

Vacuum Gauge Reading in Small Volume (Leak From Upstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

17

DPI effect rapidly vanish in few second due to large leak.

3.4E0 8.8E-1 9E-3 5E0

Pressure rise at US of DPI Pressure rise at DS of PDI

forced

  • pen

760 torr 760 cont. IPs strip

  • ff
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SLIDE 18

Vacuum Gauge Reading in Small Volume (Leak From Upstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

18

2.0E-7 with

Leaker at 760 Torr

2.3E-7 with

leaker at 760 Torr and continous

1.2E-7

When open FV

2.1E-8 2.3E-8 2.1E-8 Aug 24, 2-18

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SLIDE 19

Vacuum Gauge reading on Beamline

(Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

19

810 torr 350 torr 9.5 torr

forced close

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SLIDE 20

Vacuum Gauge Reading in Small Volume (Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

20

1.4E-5 with

Leaker at 350 Torr

4.5E-5 with

leaker at 810 Torr

1.0E-7 7.3E-9 3.8E-5 with

Leaker at 9.5 Torr

2.3E-8 Oct 1, 2-18

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SLIDE 21

Vacuum Gauge reading on Beamline

(Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

21

1.2 Torr

forced

  • pen
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SLIDE 22

Vacuum Gauge Reading in Small Volume(Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

22

~3E-8 6.1E-9 5.1E-4 with

Leaker at 1.2 Torr

2.2E-7 when

  • pen FV

Oct 8, 2-18

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SLIDE 23

Vacuum Gauge reading on Beamline

(Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

23

760 Torr Cont. 130 Torr

interlocked

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SLIDE 24

Vacuum Gauge Reading in Small Volume (Leak From Downstream of DPI)

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

24

~1.4E-8 3.0E-8 2.5E-6 with

Leaker at 760Torr, and continous

7.5E-8 when

  • pen FV

Oct 9, 2-18 5.8E-7 with

Leaker at 130 Torr

1min

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SLIDE 25

Summary of Results

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

25

1.E-07 1.E-06 1.E-05 1.E-04 1.E-03 1.E-02 100 200 300 400 500 600 700 800 900

Gas Amount Past (torr.l) Reservior Pressure (torr)

Gas Past Fast Valve in Vacuum Failures

UPSTREAM DOWNSTREAM

Leaker Reservoir CCG500 Reading dP Gas Amount monolayer coverage Leaker Location P0 (before) P1 (after) torr torr torr torr torr.liter cm2 23-Aug 1.7 6.2E-09 1.7E-07 1.6E-07 4.6E-07 1.3E-02 US DPI 52 7.5E-09 1.9E-07 1.8E-07 5.1E-07 1.5E-02 24-Aug 760 7.9E-09 2.0E-07 1.9E-07 5.4E-07 1.6E-02 760 2.3E-08 2.3E-07 2.1E-07 5.8E-07 1.7E-02 1-Oct 9.5 7.3E-09 3.8E-05 3.8E-05 1.1E-04 3.1E+00 DS DPI 350 2.1E-08 1.4E-05 1.4E-05 3.9E-05 1.1E+00 810 1.0E-07 4.5E-05 4.5E-05 1.3E-04 3.6E+00 8-Oct 1.2 6.1E-09 5.1E-04 5.1E-04 1.4E-03 4.1E+01 9-Oct 130 6.0E-09 5.8E-07 5.7E-07 1.6E-06 4.6E-02 760 3.0E-08 2.5E-06 2.5E-06 6.9E-06 2.0E-01

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SLIDE 26
  • DPI-FV protection system functions well in test, meet the

requirement.

  • The amount of gas past through FV is insignificant in term of

monolayer coverage, as result, the peak pressure short lived as soon as gas-surface rebalanced

  • The amount of gas past through FV is not directly driven by

the size of leak

  • Differential Pumping Insert (DPI) throttled the gas flux

significantly, about 2 decades.

  • Current configuration works, the amount of gas past FV is

small enough

▪ 1) not able to move particulates, ▪ 2) insignificant for surface condensation of cavities

Summary

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

26

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SLIDE 27

DPI Effect vanishing as larger leaks, however it buys a couple of second of time which is critical to minimizing gas flux into CMs

11/8/2018

  • A. Chen | Visit by Dr. Nick Gazis, ESS, and Prof. Gary Solbrekken, Univ. of Missouri

27

1.3 Torr 52 Torr 760 Torr, cont. 760 Torr