Statement of Work (SOW).pdf

Statement of Work for NASA Thermal Vacuum Chamber System

1. Overview:

This is a description of the deliverables required for the design and build of a thermal vacuum chamber system that includes the design and fabrication of one (1) vacuum chamber, one (1) thermally-controlled shroud along with required plumbing, and one (1) thermally-controlled platen, along with required plumbing for active thermal control from an external source. The thermal control unit (chiller/heater) and high-vacuum pump are not requested as part of this solicitation.

Figures in this document are intended for reference and clarity only. Other geometries and design choices including, but not limited to, cylindrical chambers/shrouds WILL be considered.

Note: If a contractor can offer similar off-the-shelf solutions that can provide significant cost/schedule savings to any of the below components that do not exactly match the dimensions given below, but the contractor believes they will satisfy the general requirements, please quote those as options as well.

2. Objective and Intended Use by NASA:

The objective of this work is to build a thermal vacuum (TVAC) chamber system that, when used with an external vacuum pump and thermal control unit, will provide a vacuum environment to simulate the radiative thermal variations that would be experienced for an optical instrument in low Earth orbit.

The intended use of this system is for actively heating and cooling internal test articles with an external chiller/heater and performing optical/laser-based interferometry measurements in a simulated space environment. NASA’s tests will involve aligning the chamber and internal test article to an input laser beam that will be reflected by our test article to exit the chamber for measurement. The TVAC system will be used to thermally cycle the test article using an external thermal control unit (e.g. Julabo Presto A45, Huber Unistat 430, or similar) to supply an ethanol-based thermal fluid to the shroud and platen system inside the vacuum chamber. Thermal uniformity and repeatability are highly desirable in this system for these tests.

Two examples of tests that will be done in this chamber are:

1) Cycle shroud and platen temperatures between 10°C and 20°C over a 90-minute period with a roughly sinusoidal temperature vs time curve.

2) Cycle the shroud and platen temperatures from -20˚C to +55˚C over a 250-minute period, hold stable for 8 hours, return to -20 C over a 250-minute period, hold stable for 8 hours.

3. Scope of Work:

The list in this section is intended as a high-level description of the deliverables, with detailed requirements provided in the following subsections. One potential concept for the vacuum chamber, shroud, and cold platen is shown for reference in Figure 1. Requirements in this SOW will reference the part names as shown in Figure 1.

Deliverables of Contractor to NASA:

1) CAD model and engineering drawings of the chamber-shroud-platen system.

2) Fully assembled chamber, shroud, platen system, as described in this statement of work.

3) Manuals and documentation that are needed for operation.

To ensure compatibility, NASA shall provide the selected contractor with:

1) Mock test article CAD model STP file (example shown in Figure 1).

2) Zemax Ray trace model STP file to check compatibility with test setup (examples shown in

Figure 10 and Figure 11).

Figure 1: Example thermal vacuum (TVAC) chamber system shown with vacuum chamber (white), thermal shroud (gray), and thermal platen (blue) installed in a horizontal test configuration with mock test article (yellow) shown for reference. Figures in this document are intended for reference and clarity only. Other geometries and design choices WILL be considered. Note, for simplicity here, the required plumbing lines for thermal control and the shroud door are not shown in these figures.

4. Vacuum Chamber Requirements:

4.1. In the following, the faces and ports of the vacuum chamber (also referred to as thermal vacuum (TVAC) chamber, or just chamber) are labeled in Figure 2 and Figure 3.

4.2. External dimensions of chamber, including mounting feet, shall not exceed 36” on any side.

Smaller dimensions preferred.

4.3. Internal dimensions of the chamber shall be determined by what is needed to achieve the internal dimensions of the shroud listed in Section 5.

4.4. The chamber shall be capable of being bolted to an optics bench having a 1” hole pattern of ¼ inch-20 thread per inch holes on a 1 inch (25.4 mm) grid.

4.5. The chamber shall have eight (8) fixed, through-hole con-flat (CF) flanges as shown in Figure 2 through Figure 4, such that there are:

4.5.1. Three 6” CF flanges on the right face (Figure 4).

4.5.2. One 6” CF flange centered on the rear face of the chamber.

4.5.3. One 6” CF flange on the left face of the chamber, concentrically aligned to Port 1 of the right face to within ±0.25 inches. (Figure 3).

4.5.4. Three 2.75” CF flanges on the left face (Figure 3), preferably evenly spaced in a line as shown, with enough separation between them to practically attach equipment.

4.5.5. All flange ports shall have enough clearance from the vacuum chamber surface to easily bolt fittings and accessories to the flange.

4.6. Port 1 (as shown in Figure 2 and Figure 4) shall be centered on the right face.

4.7. The distance between the center of Port 1 and the center of Port 2 shall be 6.25-inches horizontally (with respect to gravity), as shown in Figure 4.

4.8. The distance between the center of Port 1 and the center of Port 3 shall be 6.25-inches vertically

(with respect to gravity), as shown in Figure 4.

4.9. Port 4 shall be located on the center of the left face such that it is aligned with Port 1.

4.10. Port 8 shall be located on the center of the rear face with its center point at the same height above the base of the chamber as Port 1.

4.11. The chamber shall have flexible thermal lines to connect to the shroud and platen for active cooling.

4.11.1. E.g. Flexible 316 convoluted stainless steel lines with VCR fittings.

4.12. The door shall open outward and seal with a latch and o-ring system.

4.13. The chamber shall achieve an ultimate vacuum level below 10-5 (1e-5) Torr or better.

4.14. The chamber shall have a port to connect and pass through the thermal line from the external chiller/thermal control unit. This can either be from a dedicated port, or via an adapter that can connect to one of the 2.75” CF ports.

4.15. Optional line item: Include lifting eyes, or similar, on top exterior of the chamber for hoisting into place.

4.16. Inside the vacuum chamber on the bottom/floor, the contractor shall weld four (4) mounting pads that will protrude through the shroud’s through holes (as described in 5.9 below) for the purpose of mounting the test article and thermal platen during use. An example of this is shown in Figure 5. These mounting pads shall be drilled/tapped to each have one ¼ inch-20 thread per inch hole in the center and shall be able to support a combined mass of at least 220 lbs.

5. Thermal Shroud Requirements:

5.1. Shroud shall include thermal lines/channels for active thermal control via an external chiller/heater system with a working fluid such as water, ethylene glycol, alcohol mixes, and liquid or gaseous nitrogen.

5.2. Shroud thermal lines/channels shall be evenly distributed, as practical, to promote uniform heating and cooling.

5.3. Shroud shall be capable of routing working fluid supplied at flow rates of 25 to 115 liters/minute and flow pressures of 6 to 48 psi (i.e. from a Julabo Presto A45, Huber Unistat 430, or similar).

5.4. The working dimensions inside the thermal shroud shall be no less than 22” x 22” x 22”.

Preference is closer to 25” x 25” x 25”.

5.5. Shroud shall be actively temperature controlled with connection to thermal fluid lines.

5.6. Shroud shall have a removable or hinged door on the same face as the chamber door for removing and aligning test articles. The purpose of the door is to improve the overall thermal uniformity of the shroud, so active thermal control capability of the door is preferred. The active cooling capability of the door can be included as an optional line item.

5.7. Shroud shall have through holes that are concentric with, and have the same diameter as all ports in the chamber.

5.8. The shroud interior shall be coated to have a black finish. If the shroud is made of aluminum, anodizing is preferred. If the shroud is not aluminum, the shroud shall be painted with Aeroglaze Z-306. Coating just the inside of the shroud is preferred.

5.9. Shroud shall have four (4) through holes in the base/bottom to install platen/test article mount (that will be made later by NASA) directly to the chamber base as shown in Figure 8. The way these will work with the vacuum chamber internal mounting pads is shown in Figure 9.

5.10. To maintain compatibility with the test article and rotation of the platen, the normal distance from the center of Port 1 to the inside of the shroud floor/bottom shall be no less than 11 inches as shown in Figure 6.

5.11. To maintain compatibility with the test article and rotation of the platen, the normal distance from the center of Port 1 to the inside of the shroud rear wall (opposite the door) shall be no less than 11 inches as shown in Figure 7.

5.12. To the extent practical, the thermal shroud shall be thermally isolated from the vacuum chamber. E.g. placed on G-10 spacers to limit thermal conduction between the chamber and shroud.

6. Thermal Platen Requirements:

6.1. The thermal platen shall be capable of active thermal control via an external chiller/heater system using a working fluid such as water, ethylene glycol, and liquid or gaseous nitrogen.

6.2. Thermal platen thermal lines/channels shall be evenly distributed, as practical, to promote uniform heating and cooling.

6.3. The thermal platen shall be capable of routing working fluid supplied at flow rates of 30 to 100 liters/minute and flow pressures of 6 to 48 psi (i.e. from a Julabo Presto A45, Huber Unistat 430, or similar).

6.4. The size of platen shall be 14-inch x 14-inch, with a thickness of 2-inches or less.

6.5. The threaded hole pattern in platen shall be ¼ inch-20 thread per inch holes on a 1 inch

(25.4 mm) grid, similar to typical optics tables. Threaded holes should be made as deep as practical.

6.6. Thermal control fluid lines running between the shroud and the platen shall be flexible to allow raising, lowering, and rotation of the platen into different mounting configurations within the shroud, all without disconnecting the lines. Lines shall be flexible 316 convoluted stainless steel lines with VCR fittings, or similar.

6.7. Input and output thermal control fluid lines shall be on the same side of the platen so that it is easier to handle when rotating.

6.8. Platen can be rotated for mounting either horizontally or vertically (see Figure 10) without disconnecting thermal control fluid lines.

6.9. The platen shall be made of aluminum.

6.10. Note: Although the platen will be operated at the nominal height shown in the figures, NASA will be creating their own stand to place the platen on top of inside the shroud to set this height.

7. General Requirements:

7.1. All blind holes shall be slotted and/or use vented fasteners to avoid virtual leaks.

7.2. All plumbing shall be stainless steel or compatible with water, ethylene glycol, alcohol mixes, and liquid or gaseous nitrogen working fluids, as well as general high vacuum use.

7.3. The TVAC system shall be able to withstand cooling to -40˚C or lower.

7.4. The TVAC system shall be able to withstand heating to +80˚C or higher.

7.5. The TVAC system shall be able to reach an ultimate vacuum level of 10-5 (1e-5)Torr or better using a properly-sized turbo-molecular pump.

8. Schedule and Delivery:

8.1. Delivery as soon as possible, no later than 150 days after selection.

8.2. The contractor shall provide progress updates at least once every two weeks and participate in progress review meetings at least once per month if requested.

9. Figures:

Figure 2: Labeling of Vacuum Chamber faces and port numbers (view 1).

Figure 3: Labeling of Vacuum Chamber faces and port numbers (view 2).

Figure 4: Placement of the three six-inch CF viewport flanges on the right side of the chamber.

Figure 5: Front of vacuum chamber shown with the four internal mounting pads indicated by the green arrows.

Figure 6: Distance from Port 1 center to shroud internal floor/bottom shall be at least 11-inches to maintain compatibility with the expected mounting configurations of the platen and test article.

Figure 7: Distance from Port 1 center to the inside of the shroud rear wall (opposite the door face) shall be at least 11-inches to maintain compatibility with the expected mounting configurations of the platen and test article.

Figure 8: Shroud base/floor shown with four (4) through holes for chamber mounting posts to protrude through without contacting the shroud are shown.

Figure 9: Close-up of internal mounting pads that protrude through the shroud’s through holes, without contacting the shroud.

These will be used for mounting the test article inside the shroud.

Figure 10: TVAC system shown with the test article mounted on the platen in the horizontal configuration. Ray trace of input and output laser beams shown as blue lines. In the horizontal configuration, light enters in port 1 and exits from port 2.

Figure 11: TVAC system shown with the test article mounted on the platen in the vertical configuration. Ray trace of input and output laser beams shown as blue lines. In the vertical configuration, light enters in port 1 and exits from port 3.