Performance Work Statement Draft.pdf

PERFORMANCE WORK STATEMENT (PWS) FOR

Thermal-vacuum chamber system

United States Naval Academy

Aerospace Engineering Department

Space Systems Engineering Lab

1. Background

The United States Naval Academy (USNA) is significantly improving its current plasma research and education program through procurement of a characterization and testing system centered around a thermal-vacuum chamber. Through the Space Systems and

Engineering Laboratory (SSEL) and the Naval Academy Small Satellite Program

(NASSP), USNA actively participates in space electric propulsion research. This plasma characterization and testing system will be used to (i) provide hands-on education to the students participating in CubeSat-scale research projects and (ii) conduct advanced space plasma propulsion research. One of the core components of this system is a thermal-vacuum chamber to characterize, test and qualify (for launch) small satellites and miniature electric propulsion thrusters, and to perform basic plasma physics experiments.

The thermal-vacuum chamber will be an institutional resource available for faculty and student research projects in all Engineering Departments USNA Divisions.

The process gases that shall flow in the vacuum chamber are typical of electric propulsion systems and include:

- Noble gases: helium, neon, argon, krypton, xenon

- Atmospheric gases: nitrogen, oxygen, air

- Alternative propellants: water vapor, methanol, ethanol, sulfur, adamantane

The list of propellant is not exhaustive. Mass flow rates for noble gases shall be at most

5 mg/s, and less than 0.5 mg/s for alternative propellants.

The chamber shall initially be installed in a room that is approximately 27 ft by 14 ft, with a height under the ceiling of 11 ft. The room features

- one 15 gallon per minute water inlet providing room-temperature tap water,

- compressed air inlets, and

- a variety of 480 V, 208 V, and 120 V outlets.

An additional chilled water (< 55 F) inlet and outlet shall be installed in the room prior to delivery of the thermal-vacuum chamber system. It is expected that the chamber shall be moved to a larger space that features additional pumping capacity at a future date. The larger space features three Kinney KT500D roughing pumps installed in parallel. Each pump is boosted by a Kinney VB-2000 roots blower.

2. Objective

The objective of the acquisition of the thermal-vacuum chamber system is to provide, after a design review, a complete, functional and operational thermal vacuum system. The system shall consist of

- one vacuum chamber

- one cold plate

- one roughing pump

- one turbomolecular pump system

- one cryopump system

- three gate valves

Detailed requirements are outlined in the next section.

2.1. Vacuum chamber

2.1.1. Dimensions

The overall dimensions of the vacuum chamber are outlined in Table 1.

Table 1 – Dimensions of vacuum chamber

Dimension Minimum Maximum

Outer diameter (in.) 50 60

Inner diameter (in.) 50 54

Outer length (in.) 96 108

Inner length (in.) 96 108

2.1.2. Number of pieces

The chamber shall be split into two pieces, such that each individual piece can pass through a 54” door frame. A sealing ring (either Buna-N O-ring or CF ring) and any required bolts and nuts shall be provided to provide the seal between the two pieces.

2.1.3. Door

A door that can be actuated by hand and that is able to seal one side of the chamber shall be provided. The chamber shall have a hinge to support the door.

The door shall be installed on the chamber by the contractor prior to shipping. If the assembly of the chamber section and the door does not fit within the 54” door frame, the door shall not be installed on the chamber.

Instructions for door assembly and maintenance shall be provided to the client.

Ports and windows

Door The door shall have a 10” CF port with a quartz window mounted on it

Chamber top The top of the chamber shall have a 10” CF port with a quartz window mounted on it. Four additional ports that are of a size that is compatible with both gate valves and high-vacuum pumps shall be installed on top of the chamber. The size of the ports shall be determined after a design review.

Thermal plate a 4.5” CF port with one VCR outlet and one VCR inlet shall be installed for the liquid circulating in the thermal plate.

Additional details all ports shall have a standard orientation that is radial. The exact number of ports and windows and their locations shall be determined after a design review with the contractor and prior to manufacturing of the chamber.

2.1.4. Frame

A frame shall be provided to support the chamber. Casters and adjustable feet shall be installed on the frame. The frame shall be able to be split to support each individual piece of the chamber.

2.1.5. Materials

The chamber and door shall be made of 304 stainless steel and aluminum, respectively.

The chamber shall be machined using machine coolant that is sulfur free.

2.1.6. Miscellaneous

The chamber shall be cleaned and ready for use when received the customer.

All vacuum chamber ports shall be covered prior to shipment.

All welded components shall be tested with a helium mass spectrometer, to a leak rate of

5x10-9 STD cc/s or better.

All necessary O-rings and CF copper rings shall be included.

2.2. Thermal plate

2.2.1. Dimensions

The thermal plate shall have the following dimensions:

- Depth: 36”

- Width: at least 36”, and at most 40”

- Height: 1”

2.2.2. Materials

The thermal plate shall be made of aluminum.

The liquid coolant line shall be made of copper tubing. The coolant line shall be brazed or welded onto the aluminum plate.

2.2.3. Miscellaneous

The thermal plate shall have tapped holes of size ¼”-20 with 2” x 2” spacing. The working fluid circulating in the thermal plate is expected to be at a temperature in the (inclusive) range of -55°C to 150°C. The thermal plate assembly shall be able to process fluids within that temperature range without any adverse effect on the established vacuum.

2.3. Pumps

The pumping system shall maintain a vacuum level in the chamber of at most 10 μTorr with gas flowing within the chamber, and at most 1 μTorr without gas flowing. The typical gases considered are outlined in Section 1. In order to capture both heavy (e.g., xenon) and light (e.g., nitrogen) gases and maintain high-vacuum, both a turbomolecular and cryogenic pump shall be provided. The high-vacuum pumps (turbomolecular and cryopumps) shall be backed by a roughing pump.

Without gas flow, the time to reach the cross-over pressure and high-vacuum pressures

(< 1 μTorr) shall be less than 15 minutes and 45 minutes, respectively.

2.3.1. Roughing pump

The roughing pump shall:

- be able to bring the vacuum chamber to a pressure that is low enough so that it is safe for the high-vacuum pumps to operate (i.e., the roughing pump has a pumping capacity that is enough to reach “cross-over pressure”)

- be a “dry” vacuum pump (e.g., screw pump)

- have a maximum pumping speed of no more than 250 m3/hr

The roughing pump assembly shall have casters.

2.3.2. Turbomolecular pump system

The turbomolecular pump system shall consist of

- A turbomolecular pump

- A control unit for the turbomolecular pump

The turbomolecular pump shall

- be water-cooled o the required flow temperature shall be below 32°C o the required flow rate shall be below 5 L/min

- have a minimum pumping speed of 3,000 L/s for nitrogen gas

- be able to be mounted on the vacuum chamber in any orientation

Electric propulsion test articles and plasma devices that feature magnetic fields (≤ 1 T in the test article) shall be tested in the vacuum chamber. The turbomolecular pump shall be compatible with those expected magnetic fields. The turbomolecular pump does not need to operate if strong magnetic fields are expected.

2.3.3. Cryogenic pump system

The cryopump system shall consist of:

- A cryopump that is installed on the vacuum chamber

- A compressor that provides the cryogenically cooled working fluid for the cryopump

- A control unit for the compressor and pump

- Pressure lines for the cryogenically cooled working fluid

The compressor shall

- be water-cooled o The required flow temperature shall be below 32°C o The required flow rate shall be below 10 L/min

- operate with helium as the cryogenic fluid

The cryopump shall

- be compatible with the cryo compressor

- have a minimum pumping speed of o 2500 L/s for argon o 3000 L/s for nitrogen

- be able to be mounted on the vacuum chamber in any orientation

The control unit shall be integrated with the compressor.

The pressure lines shall be compatible with the working fluid and be flexible.

2.4. Valves

Valves that are compatible with the pumps and chamber flanges shall be provided. No adapters shall be required to install the valves on the pumps and the flanges.

2.4.1. Gate valves

The cryopump, turbopump, and roughing pump shall be individually isolated with gate valves, as shown in Figure 1.

Figure 1 - Schematic of vacuum chamber with pumps and gate valves installed

The gate valves shall:

- be air-operated o The minimum and maximum air pressure shall be 5 PSIG and 80 PSIG, respectively

- have a solenoid valve to control the application of the air pressure on either side of the gate valve piston o the solenoid valve shall have a nominal operating voltage of 12 VDC

- specified to the customer

2.4.2. Venting valves

Foreline

A venting valve shall be installed on the roughing pump foreline. The valve shall:

- be air-operated o The minimum and maximum air pressure shall be 5 PSIG and 80 PSIG, respectively

- have a solenoid valve to control the application of the air pressure on either side of the gate valve piston o the solenoid valve shall have a nominal operating voltage of 12 VDC

- specified to the customer

Vacuum chamber

A valve shall be installed on the vacuum chamber to vent the chamber from vacuum back to atmospheric pressure. The valve shall be manually actuated. The exact size and location of the valve will be determined after a design review and specified to the customer.

3. Scope

The scope of this effort is the acquisition of a thermal-vacuum chamber and associated accessories.

4. Task requirements

This contract will purchase a thermal-vacuum chamber system that fulfills the outlined requirements. The contractor will work with the customer to finalize a chamber design.

5. Deliverables

The contractor will first deliver a design review. After acceptance of the proposed design, the contractor will deliver the complete thermal vacuum system, which consists of

- one vacuum chamber,

- one cold plate,

- one roughing pump,

- one turbomolecular pump system,

- one cryo pump system,

- three gate valves,

- any supporting software,

- any required cables, hoses, vacuum flanges, O-rings, CF flanges, and

- technical documentation, specifications, and manuals.

All elements of the complete thermal vacuum system shall fulfill the requirements outlined in Sections 1 and 2.

6. Payment

Payment for the equipment will occur via contracting.

7. Period of performance

The period of performance is expected to be before August 1, 2025.

8. Quality assurance

The contractor shall inform the client if, after calculations, the pumping system cannot process the maximum expected gas flow rate. If that is the case, the contractor shall provide the client with a new estimate of the maximum mass flow rate that the system can process.

The contractor shall inform the client if gate valves outlined in Figure 1 must be positioned at a different location, or if a gate valve is unnecessary to achieve the desired performance.

The contractor shall be responsible for ensuring that all flanges are compatible between vacuum pumps, gate valves, and the chamber.

Acceptance testing shall be performed by the contractor. The customer shall be present to inspect the system prior to shipment.

Any software and firmware updates shall be communicated and be made available to the customer. The contractor shall provide technical support upon request.