21-01570 Specifications.pdf

SPECIFICATIONS

CRYOSTAT PROTOTYPE

The National Institute of Standards and Technology (NIST), along with the Superconductive Electronics Group (SEG), develops and disseminates Josephson Voltage Standard (JVS) systems as a standard reference instrument (SRI). As part of disseminating an SRI JVS system, the SEG requires a cryostat that can provide at least 250 mW of cooling power at temperatures below 4.5 K. This cryostat is required to cool packaged chips containing arrays of Josephson junctions, which are the key component of the JVS system. For the Josephson junctions to operate correctly, the SEG also require that the cryostat has temperature fluctuations less than 20 mK peak-to-peak at 4 K near the chip, that it is compatible with our chip packages (both mechanically and electrically), that it is electrically isolated, and that it is magnetically shielded.

This request is for one cryostat; however, the Government reserves the right to purchase up to five additional cryostats within fiscal years ‘22 and ‘23.

The cryostat system shall comply with the following cryogenic specifications:

1. The cryostat system shall have a base temperature less than 3.5 K at the JVS chip package and more than 250 mW of cooling power at 4 K at the JVS chip package after delivery, that is, with all of the wiring installed and connected to the JVS chip package.

In addition, the cryostat system shall have less than 20 mK peak-to-peak temperature fluctuations at 4 K at the JVS chip package after delivery, that is, with all the wiring installed and connected to the chip package, which may be dissipating up to 250 mW.

2. The cryostat system shall include a thermometer on the 4 K plate which holds the JVS chip package, a heater on that 4 K plate, and a temperature controller which can read the thermometer temperature at a speed greater than or equal to 5 samples/sec with a resolution better than 3 mK (at 4 K) and can stabilize the temperature of the plate at any temperature between 3 K and 25 K using the thermometer and heater. In addition, the controller shall be equipped with a manual heater output control, allowing to user to add a predefined power on top of the PID control loop to be dissipated in the heater.

3. The cryostat system shall have a thermal radiation shield at approximately 45 K.

4. The cryostat system shall be cryogen-free; that is, the user shall add no additional cryogens after delivery.

5. The cryostat system shall have a water-cooled compressor and should consume less than

5 kW of power.

6. The cryostat system shall have flexible lines between the compressor and the coldhead that are at least 5 m long.

7. The cryostat system shall include a vacuum pump and sufficient parts to evacuate the cryostat before cooldown.

The cryostat system shall comply with the following mechanical specifications:

8. The cryostat system shall fit within a standard 19-inch rack; it shall be less than 30 cm in diameter and less than 61 cm tall.

9. The cryostat system shall have a gold-plated oxygen-free-high-conductivity (OFHC) copper 4 K plate large enough to hold four NIST JVS chip packages with the correct mounting holes. The JVS chip package is 2.54 cm wide by 5.75 cm long; the RF coax is connected in the “long” direction, so additional length is required to fit the SMA connectors and coax.

10. The cryostat system shall have at least 7 cm in the vertical direction between the 4 K plate and the approximately 45 K radiation shield.

11. The cryostat system shall have at least one blank vacuum flange.

The cryostat system shall comply with the following electrical specifications:

12. The cryostat system shall include quantity one 0.086 inch diameter RF coax with BeCu outer and silver-plated BeCu inner; it shall be heat-sunk at both approximately 45 K and at 4 K; it shall be arranged so that it can be connected to the NIST chip package; it shall have SMA connectors on both the vacuum/room-temperature side and on the JVS chip package side without any intermediate connectors. In addition, it shall have an SMA vacuum feedthrough to room temperature/pressure.

13. The cryostat system shall have a total of 25 resistive phosphor bronze dc wires; the resistance per wire shall be less than 10 ohms; the wires shall be in a single loom of 25 wires each; the loom shall be terminated in a 25-pin microD connector at 4K and a 25-pin DSUB connector at room temperature/pressure; the wires in the loom shall be arranged in twisted pairs according to the connector pin numbers: 1-14, 2-15, 3-16, 4-17, 5-18, 6-19, 7-20, 8-21, 9-22, 10-23, 11-24, and 12-25, with a single wire at pin 13; and the loom shall be heat-sunk at both approximately 45 K, and at 4 K. The isolation resistance between the loom and the cryostat and between every pair of loom wires shall be at least 100 GΩ.

14. The cryostat system shall have a total of four 34 AWG or larger copper magnet wires arranged in two twisted pairs for precision voltage measurements; they shall be continuous (including no solder joints or connectors) from room/temperature pressure to the 4K stage; they shall be fed-through to room temperature/pressure with at least 10 cm of wire at room temperature/pressure; they do not need to be terminated; they shall be isolated from the cryostat and feedthrough to room temperature; the isolation between the cryostat and the wire, and between the wires, shall be at least 100 GΩ; each pair shall be heat-sunk at both approximately 45 K and at 4 K with at least 10 cm of wire after the 4 K heat sink, and the total length of each wire shall be less than 60 cm and should be as short as possible.

15. The cryostat system shall include passive magnetic shielding located in the vacuum made from Mu-metal, Cryoperm, or similar material. The shield shall reduce the magnetic field at the chip package to less than 0.01 times the earth field.

16. The cryostat and 4 K plate shall be electrically isolated from the compressor.

The cryostat system shall comply with the following maintenance specifications:

17. There shall be a plan for cryocooler maintenance which may require an additional fee, including an option for on-site maintenance, an option for shipping the cryostat to a vendor, and an option for performing maintenance without disassembling the wiring or disconnecting the JVS chip package (for example, by performing maintenance without removing the cryocooler from the cryostat).

The cryostat system shall comply with the following documentation specifications:

18. All manuals shall be provided electronically

Commercial Product Requirements The original manufacturer's full warranty shall cover the new cryostat system. The use of “gray market” components, refurbished or reconditioned items, are not acceptable.

INSPECTION AND ACCEPTANCE

The Government acceptance is expected up to seven business days. NIST personnel is subject to COVID-19 guidance and restrictions as applicable.

SHIPPING AND DELIVERY

Maximum of six months after receipt of order (ARO).

WARRANTY

Manufacturer warranty from the date of NIST acceptance.

Commercial Product Requirements