Design of Vacuum Chambers of SSRF Storage Ring Yonglin. Chen, Dikui. Jiang SSRF Vacuum Group Shanghai Institute of Applied Physics(SINAP) China Academy of Sciences

Key points of chamber design 1, The structure of chambers, material, strength, magnetic permeability 2, Mechanical stability, support, baking in-site 3, Thermal stability, thermal calculation, cooling

A cell

Structure of chambers BSC:32mmX64mm(VXH), beam chamber:35mmX68mm (VXH) SLOT:13mm X76mm (VXH)

Relation between the chambers and the magnets QMSM Chamber QMSMCM

BM Chamber BM

SR exit port The dimension of the IDSR exit port of the chambers is decided by both the drew IDSR and the leaking BMSR.

Typical QMSM chambers(1) e BPM blocks Outer ribs Absorber and pumping portsPumping ports

Cross section The Up Plate The Down Plate TIG without flux The Up Plate The Down Plate Formed by CNC edge bending machine

Profile of chamber The BPM BlockThe FlangeThe Flange Tube The Body of the Chamber Inner ribs

BPM block Welded with chamber body by TIG Welded with BPM by TIG Alignment target apertureSupport aperture

Upstream and downstream flanges

BPM block Outer ribs Exit ports of BMSR Port of absorber Port of absorber e Typical QMSM chambers(2)

Inner supports

Typical BM chamber Pumping portsOuter ribs Chamber body Rectangular flange CF flange Absorber port Fixing slot blocks port Fixing inner blocks ports

Inner ribs Slot blocks with cooling tubes Inner block Up slot block Down slot block

Fixing the cooling tubes to the Cu slot blocks by hammering cooling tube Chamber body Cu slot block

BM chamber drew infrared beam Gateway for infrared beam: -10mrad~25mrad×±8.9mrad(H ×V ) The groove for drew infrared beam

Smooth transition of inner wall of chambers The transition form QMSM chambers to BM chambers.

 There are some steps in the region where the chambers are welded with flanges or BPM blocks because the shapes of the chamber bodies may be different with those of the flanges or BPM blocks. The height of the steps is less then 0.5mm. Height of step<0.5mm

Maximum deformation under atmosphere pressure

Development of 3m chamber model The goal of R&D: (1) To decide feasibility of SS chambers in Chinese factories (2) To decide better process

Parameters

Specification of the planenss and straightness of chambers The specification: Planenss: less then 0.5mm/each plane for 3m chamber Straightness : less then 1mm for 6m chamber Note:  The supports in the BPM blocks do great contribution to the Planenss of the chambers, but do nothing to the Straightness of the chamber.

Connection of chamber bodies and flanges or BPM blocks Connection methods in the chamber model New design

Mechanical stability and in-site baking  When the chambers are in-site baking, how to deal with the XY fixed support, fixing it or relaxing it or add a spring to restrict it in X direction ?

Primary thermal loads on chambers: (1) Power from BMSR (2) Power from absorbers because of fluorescence scattering (3) Thermal load because of HOM lost

Power on the chambers from BMSR

5% of the power on absorbers will be fluorescence scattered to the chambers. A cell

Thermal load because of HOM lost: normal BPM: 4.12W high precision BPM: 7.11W

Maximum power and power density is in the SR-VA-01VC-2 chamber.The temperature in the Cu slot blocks will be elevated about 5.2 ℃.

As to the QMSM chambers without cooling, the maximum power and power density are in the SR-VA-01VC-6 chamber.The temperature near the BPM and absorbers will be elevated about 3.3 ℃.

During commissioning, the BMSR and IDSR may drift and bomb the chambers continuously when the interlock system doesn't work. BMSR : I=50mA IDSR:I=10mA

(1) I=50mA, QMSM chamber without water cooling. Chamber body T max ＝ 160 ℃ Upstream flange T max ＝ 167 ℃ (2) I=50mA, BM chamber with water cooling. Cu slot blocks T max ＝ 65.3 ℃ Cooling Water T max ＝ ℃ (3) I=10mA, IDSR+BMSR bomb BM chamber continuously with water cooling. Cu slot blocks T max ＝ 94.2 ℃ Cooling Water T max ＝ 82.4 ℃

During normal running, the interlock system must work in a certain time when the BMSR and IDSR drift and bomb the chambers, otherwise the following accidents may be taken place: (1) The temperature of the chambers will be elevated rapidly, which will lead to plenty of desorption. (2) The the cooling water will reach the boiling point,which will arose the libration of cooling tubes. (3) The chamber will be melted. Specification: Tmax=100 ℃

I=400mA ， the QMSM chamber without cooling After 0.4 s, Chamber body: T ＝ 100 ℃ ! The interlock system must work in 0.4s when the beam drift seriously..

BMSR bomb the inner wall of chambers Interlock threshold value: ID-BPM: X max =± 2.5 mm ， Z max =± 0.5 mm N-BPM: X max =± 2.5 mm ， Zmax=±1.0 mm Some BMSR will bomb the inner wall of the Chambers, P=~3 W/cm 2 Chamber inner wall Beam BMSR bombing region

The temperature in the inner wall of the QMSM chamber will be elevated 24.3 ℃ without cooling. The temperature in the inner wall of the BM chamber will be elevated less than that.

Cooling for QM/SM Chambers  According to the calculation, the QMSM chambers needn’t be cooled.  We fix cooling water tube on QM/SM chamber conservatively. Chamber body Cooling tube Aluminum foil Fixing bolt

THANKS !