System weight and support structure

The new setup needs to be placed somewhere in the DMI laboratory. To this end, a support structure needs to be provided, preferably one that can be moved. Out of cost-consideration, a support is constructed from a setup that is already present in the laboratory.

5.3.1 List of system components and weight

The mass of complete system is determined; this is of interest for the required support. It must be noted that this is just presented as an indication. The support is already present in the laboratory of DMI and no structural calculations are carried to indicate whether this support will indeed suffice. The weight of commercial parts is retrieved from datasheets. The weight of designed parts is determined by retrieving their volumes from SolidWorks. These values are multiplied by the

specific weight of the used stainless steel AISI 304, which is has a mass density of 8000 kg m-3 _(33).

All parts and corresponding masses are shown in Table 5.1 on the next page.

Note that the masses for the flanges are also estimated using SolidWorks, because the LNLS Handbook (26) does not provide this information. With all weights added in the table, a total weight of about 181 kg is assumed for the complete system. The weight for bolts and nuts is estimated and the weight computation by SolidWorks is an approximation. The calculated value is for that reason an indication rather than an exact prediction of the total weight. If the large gate valve would be added as protection for the ion pump, an approximate weight of 16.8 kg must be added (MDC 300018).

5.3.2 Support structure

With the system dimensions and weight known, the support structure can be provided. DMI wants to make use of a rack that is already present in the laboratory, shown in Figure 5.2a (page 53). This rack is a table from which the top can be removed. The CAD-model is used to confirm that the FERP-system fits on this rack. See Figure 5.2b. From this figure it is clear that a bridge needs to be created between the two long bars on the bottom, on location A in the figure. Furthermore, the large quantity of mass concentrated in the arm of the small sphere creates a significant moment the bolts in the main chamber. A bar should be created between the small bars of the rack and the nipple between the small sphere and (right) gate valve, on location B. The position of the bottom support determines the position of this nipple and should therefore be placed exactly.

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Part Product Code (Manufacturer) Mass (kg) Pcs

Large spherical cube MCF600-sphcube-F6C8 (Kimball Physics) 16.54 1

Small spherical cube MCF450-sphcube-E6A8 (Kimball Physics) 3.81 1

Ion pump 400L (Gamma Vacuum) 67.0 1

Small gate valve 300014 (MDC) 4.99 2

Diaphragm Pump MVP 015 (Pfeiffer Vacuum) 6.5 1

Turbo pump Hi Pace® 80 (Pfeiffer Vacuum) 3.8 1

Transfer arm 665100 (MDC) 4.54 1

FERP-HEAD (constructed at CTI, estimated weight) 2.0 1

Nipple 1 (turbo-molecular pump – small gate valve) 1.93 1

Nipple 2 (small gate valve – small sphere) 1.93 1

Nipple 3 (small sphere – small gate valve) 1.85 1

Nipple 4 (small gate valve – large sphere) 3.17 1

Nipple 5 (large sphere – large gate valve) 5.71 1

Crossing 9.18 1

TSP-Cryoshroud (Gamma Vacuum) 9.0 1

Residual Gas Analyzer (Stanford Research Systems) 2.1 1

Pirani gauge ConvecTorr (Agilent Technologies) * 0.3 1

Combination gauge FRG700 (Agilent Technologies) 0.98 1

Hot-cathode gauge Bayard Alpert UHV-24p (Agilent Technologies) * 1.0 1

Viewport large sphere MCF600-mtgflg-F1VP (Kimball Physics) 1.93 1

Viewport small sphere MCF450-mtgflg-E1VP (Kimball Physics) 0.80 1

CF16 blank flange CF16CG 0.04 8 CF40 blank flange CF40CG 0.35 8 CF63 blank flange CF63CG 1.31 1 CF100 blank flange CF100CG 2.66 2 CF150 blank flange CF150CG 5.31 2 Converter flange CF63 to CF40 CF63DF-40 1.09 2 Converter flange CF100 to CF63 CF100DF-63 2.11 1

Bolts and nuts (estimated weight) 2.0 1

Total mass 180.7 kg

Table 5.1 – all system parts and corresponding mass

The bottom bridge is created using two steel bars and a thick bottom plate. For the bars, a steel T- section profile from the laboratory is used (the bottom bars of the rack are thin-walled square profiles). A plate is used for the positioning of the ion pump. This plate does not have a structural function and should therefore be thin and light. For all parts of the support, the exact steel type is not known, because these are old parts from the laboratory.

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Figure 5.2 – a) available rack from DMI laboratory and b) CAD-model for placing FERP-system Figure 5.3 shows the design of the support. Appendix D contains technical drawings that show the design of the plate and its exact placement on the rack. The bottom plate is designed in that way, that the bottom flange of the ion pump fits exactly in it. It is left to the opinion and experience of the workshop how these bars and plate can best be fixed onto the rack. The support between the rack and the nipple, which should be created top-right in Figure 5.3, is not further discussed in this report. Furthermore, Vinicius L. Pimentel assures on experience that the complete steel support is appropriate to carry the load imposed by the system. No structural calculations are carried out to confirm this statement.

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Figure 5.4 shows the convenience of the use of the rack for the support structure. It can be closed using thin metal plates for the bake-out procedure. The required temperature of 150 °C inside this ‘oven’ can be obtained using the heating system of the ion pump. As a reminder, Figure 3.14 showed the cover used for the bake-out of a STM. Because the system needs to be completely closed, there must still be a structure designed that can be placed on top. This is not further discussed here.

Figure 5.4 – rack can be closed for bake-out

It was mentioned that it is preferred that the support structure can be moved. To this end, four small wheels from the laboratory are used to fix underneath the legs of the rack.

Once the support is completed, all heavy vacuum equipment can be placed in position using a small crane. Then, the system can be cleaned, a bake procedure can be carried out, the system can be pumped down to 5x10-12 Torr UHV and the FERP-experiment can be started. This concludes the internship assignment.

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