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Lakeshore RGC4 User Manual

Cryogen-free recirculating gas cooler
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User's Manual
Model RGC4
Cryogen-Free
Recirculating Gas Cooler
Lake Shore Cryotronics, Inc.
575 McCorkle Blvd.
Westerville, Ohio 43082-
8888 USA
sales@lakeshore.com
support@lakeshore.com
www.lakeshore.com
Fax: (614) 891-1392
Telephone: (614) 891-2243
Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics,
Inc. No government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates
proprietary rights of Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus disclosed herein may be subject
to U.S. Patents existing or applied for.
Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify, or withdraw functions, design modifications, or products
at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or consequential damages
in connection with furnishing, performance, or use of this material.
Rev. 1.1
P/N 119-107
2 October 2024
|
www.lakeshore.com

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  • Page 1 User’s Manual Model RGC4 Cryogen-Free Recirculating Gas Cooler Lake Shore Cryotronics, Inc. 575 McCorkle Blvd. Westerville, Ohio 43082- 8888 USA sales@lakeshore.com support@lakeshore.com www.lakeshore.com Fax: (614) 891-1392 Telephone: (614) 891-2243 Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc.
  • Page 2 Product (such as probe tips and cables, probe holders, sample tails, rods and holders, ceramic putty for mounting samples, Hall sample cards, Hall sample enclosures, etc.); or, (d) non-Lake Shore branded Products that are inte- grated with the Product. Model RGC4 Cryogen-Free Recirculating Gas Cooler...
  • Page 3 Copyright 2024 Lake Shore Cryotronics, Inc. All rights reserved. No portion of this manual may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the express written permission of Lake Shore. www.lakeshore.com...
  • Page 4 Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 5: Table Of Contents

    3.3.4 Uncrating the RGC4 Cryostat ........
  • Page 6 4.7 Room Temperature Helium Circulation..........35 4.8 RGC4 and Continuous Flow Cryostat Initial Cooldown ......36 4.9 Optimizing the Circulation for the Lowest Base Temperature...

  • Page 7: Chapter 1: Introduction

    RGC4 cryostat for re-cooling and continuous recirculation. 1.3 Specifications Full specifications about the RGC4 series are provided on our website. Please see the Technical Specifications page at https://www.lakeshore.com/rgc.

  • Page 8: Safety Summary And Symbols

    Shore Cryotronics, Inc. assumes no liability for customer failure to comply with these requirements. The RGC4 protects the operator and surrounding area from electric shock or burn, mechanical hazards, excessive temperature, and spread of fire when used as directed in the manual. Environmental conditions outside of the conditions below may pose a hazard to the operator and surrounding area.
  • Page 9 Three-phase alternating current (power line) yellow; symbol and outline: black Earth (ground) terminal CAUTION or WARNING: See instrument documentation; background color: yellow; Protective conductor terminal symbol and outline: black Frame or chassis terminal On (supply) Off (supply) FIGURE 1-1 Safety symbols www.lakeshore.com...
  • Page 10 CHAPTER 1: Introduction Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 11: Chapter 2: System Overview

    2.2 Major This section is intended as a reference for identifying various components, operator interfaces, and controls called out in later chapters. An RGC4 system is comprised of Components the components listed below.

  • Page 12: System Components

    Components 2.2.1.1 RGC4 Cryostat The RGC4 cryostat is used to cool and liquefy recirculating helium, which is then delivered to the continuous flow cryostat for cooling the sample, device, or process. The recirculating gas is first cooled as it passes through a series of internal heat exchangers.
  • Page 13 FIGURE 2-5 Closed cycle refrigerator (CCR) 2.2.1.1.2 Flexible Vacuum Insulated Transfer Line A flexible transfer line is integrated into the outer vacuum shroud of the RGC4 cryostat. It is connected internally to the recirculating helium gas circuit. 2.2.1.2 CCR Compressor The CCR compressor is required in order to operate the CCR.
  • Page 14 D V3: helium storage tank valve D V4: helium storage tank evacuation and fill valve D V5: helium circulation and collecting valve D V6: helium circulation line return valve, located on RGC4 cryostat top flange (see FIGURE 2-4) D V7: zeolite trap outlet valve...
  • Page 15 Helium LHe cryostat input circulation Vent port heater line Exhaust gas to pump Return gas to RGC Vibration isolator Cryostat outlet line He storage tank Pump Cold head Helium return line Zeolite trap FIGURE 2-7 Gas handling system diagram www.lakeshore.com...
  • Page 16 Vibration isolator 2.2.1.6 Temperature Controller A Lake Shore temperature controller is connected to the RGC4 cryostat for monitoring and controlling the internal silicon diode temperature sensors and heaters. Systems may be configured to either use the same temperature controller as the continuous flow cryostat, or a second temperature controller.
  • Page 17 Optional turbomolecular vacuum pumping system 2.2.1.9 Continuous Flow Cryostat (optional) The RGC4 can be used as a source of cooling for almost any Lake Shore continuous flow cryostat, as well as continuous flow cryostats from other manufacturers. Common Lake Shore cryostats include:...
  • Page 18 The RGC4 uses circulating helium gas to provide cooling to the continuous flow cryostat. The RGC4 system is shipped with a full charge of helium gas. Certain maintenance procedures (as described in Chapter 6 of this manual) require adding or replacing the helium gas.

  • Page 19: Chapter 3: Installation And Setup

    6 to Requirements and 20 m (20 to 66 ft) from the RGC4 (depending upon the specific CCR model). However, Suggested Layout the optional turbomolecular vacuum pumping system must be located within 2 m (6.6 ft) of the RGC4 cryostat for optimum performance.

  • Page 20: Environmental Requirements And Concerns

    3.2.2.3 Ventilation Place the RGC4 and all components in a well-ventilated area to avoid the risk of asphyxiation from helium gas in the event of accidental release from the CCR compressor or recirculating gas circuit.

  • Page 21: Power Requirements

    75 A 20 A AC 480 V/60 Hz (50/60 Hz) * It is recommended to use a 50 A circuit breaker with the FA50L compressor, and a 30 A circuit breaker with the FA50H compressor. TABLE 3-3 3-phase power requirements www.lakeshore.com...

  • Page 22: Water Requirements

    Water pressure may be difficult to control if the RGC4 uses a shared building water line. Large seasonal variation in temperature can also cause problems. High water temperatures in the summer months may exceed the specified temperature requirement.

  • Page 23: Vacuum Requirements

    <5 x10 Torr in the RGC4 cryostat while at room temperature. A vacuum isolation valve with an NW 25 flange is included on the RGC4 vacuum shroud. Lake Shore offers the TS-85-D turbomolecular vacuum pumping system for evacuating the RGC4 cryostat and other system components.

  • Page 24: Unpacking The Rgc4 System

    Clear enough space in the lab to complete all steps safely. 3.3.1 Shipping The standard components of the RGC4 system will be shipped in several boxes and crates. TABLE 3-6 lists approximate size, weight, and contents of the standard Containers shipping containers.

  • Page 25: Uncrating The Rgc4 Cryostat

    3. Remove any bracing using a T-25 Torx head screwdriver. 4. Remove any plastic wrap covering the RGC4. 5. Attach the lifting straps and shackles to the lifting eyes on the RGC4 cryostat. 6. Remove the screws securing the RGC4 cryostat to the base of the crate.

  • Page 26: Uncrating The Gas Handling System (Ghs) And Vibration Isolator

    Hitting the equipment with a sharp edge or pointed object may cause explosion or rapid escape of gas. The compressor should not be tilted by more than 30°, as this may cause damage to the compressor capsule, or oil contamination of the helium gas line. Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 27: Uncrating The Remaining Components

    3.3.7 Uncrating the Uncrate the remaining components carefully: Temperature controller(s) Remaining Flexible hoses and circulating helium gas lines Components Electrical cables Other options: D Optional continuous flow cryostat D Optional turbomolecular pumping system D Optional recirculating chiller www.lakeshore.com...

  • Page 28: Utility Connections

    3.4 Utility Use the following procedures to complete the utility connections required for the RGC4 system. The items in this section must be completed prior to the arrival of a Connections Lake Shore representative for installation and training. You may also need to refer to the CCR compressor and cold head manual for further information.

  • Page 29: Assembling The Rgc4 System

    To minimize the audible noise of the compressor (70 dBA at 1 m) at the RGC4 during operation, the compressor may be located in an adjacent room with the flexible lines and power cable routed through an opening in the wall.

  • Page 30: Connecting The Ccr Compressor To The Ccr Cold Head

    3.5.3 Connecting the The flexible helium lines and electrical cable must be connected to the CCR cold head located on the RGC4 cryostat and to the CCR compressor unit. Read the warnings and CCR Compressor to the cautions below prior to following the steps to make these connections.
  • Page 31 Ensure the compressor main power switch is off before connecting or disconnecting the cold head electrical cable. 1. Ensure that the power switch on the compressor is off. Compressors vary; the power switch may be different. FIGURE 3-8 Compressor main power switch in off position www.lakeshore.com...

  • Page 32: Connecting Vacuum And Helium Gas Flexible Tubing

    (GHS) vacuum circulation pump (section 2.2.1.4) valve V1 using the helium circulation line F2. 4. Connect the RGC4 cryostat (section 2.2.1.1) valve V6 inlet port to the GHS (section 2.2.1.4) valve V7 using the helium return line F3. 5. Insert the RGC4 cryostat vacuum insulated helium transfer line (section 2.2.1.1.2) fully into the continuous flow cryostat inlet port...

  • Page 33: Connecting The Temperature Controller Cables

    3.5.5 Connecting the Connect the temperature controller cables as follows: Temperature Controller 1. Connect the supplied instrumentation cable between the RGC4 cryostat electri- cal connector (mounted on the cryostat top flange) and the temperature control- Cables ler, according to the cable labeling.

  • Page 34: System Verification And Testing

    RGC4 cryostat. The RGC4 should be under vacuum for this test, although Test the test can be performed even if the RGC4 cryostat has not yet been evacuated. Use the following steps to test the CCR operation: 1. Press ALL OFF on all temperature controllers to ensure that all control outputs have been turned off from any previous sensor and heater test.

  • Page 35: Verifying The Temperature Controller Settings

    2. Verify heaters have the correct resistance using a multimeter. This is typically 25 ohms, refer to the wiring diagram in this manual for details. Under normal operation the RGC4 system heaters are not needed. The heaters are only used in certain troubleshooting scenarios.
  • Page 36 CHAPTER 3: Installation and Setup Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 37: Chapter 4: Operation

    Operational Mistakes These mistakes can result in costly damage to the system. Please read this chapter thoroughly before operating the RGC4 system for the first time so that these and other mistakes can be avoided. Opening the RGC4 cryostat or continuous flow cryostat vacuum chamber to atmosphere while the system is cold.

  • Page 38: Turbomolecular Vacuum Pumping System Basic Operation

    4.3.1.1 Vacuum Isolation Valve The RGC4 cryostat vacuum chamber and turbomolecular vacuum pumping system are separated by the vacuum isolation valve located on the top flange of the RGC4 cryostat. The valve has two potential uses during operation, to help maintain the...

  • Page 39: Closing The Vacuum Isolation Valve During Operation

    Refer to Chapter 6 of this manual for troubleshooting information. To prevent wear over time, the RGC4 cryostat may need to be warmed up and re- evacuated if it has been in continuous operation for several months. Even with properly functioning equipment and good maintenance, vacuum performance of the RGC4 may degrade with time.

  • Page 40: Initial Gas Handling System (Ghs) Evacuation And Leak Test

    6. Continue turbo-pumping for at least 8 h (preferably overnight) to purge the residual helium gas from the system on first operation of the RGC4, or if the GHS or any interconnecting hose has been vented to atmosphere for any reason.

  • Page 41: Rgc4 Cryostat Evacuation

    7. Close valve V8, and shut off (and vent) the turbo vacuum pump. 8. Close valves V6 and V7. 9. Confirm that valves V1, V2, V3, V4, V5, V6, V7, V8 and V9 are closed and the RGC4 cryostat needle valve is open (5 turns).

  • Page 42: Rgc4 And Continuous Flow Cryostat Initial Cooldown

    The CCR compressor must not be started/stopped greater than 6 times/h or 24 times/day. Observe a 3 min wait interval from the time it is switched off prior to switching it back on. Frequent on/off cycling may result in damage or compressor malfunction. Model RGC4 Cryogen-Free Recirculating Gas Cooler...
  • Page 43 If the CCR compressor does not operate as expected, or if the RGC4 does not begin to cool, refer to the troubleshooting information in Chapter 6. 7. Confirm that the RGC4 cryostat needle valve is fully open (5 turns). 8. The RGC4 cryostat inlet pressure (G3) will slowly reduce during the system cooldown.

  • Page 44: Optimizing The Circulation For The Lowest Base Temperature

    Proceed with experimental measurements (section 4.10). 4.9.2 Optimizing 1. Follow the initial cooldown procedure described in section 4.8. 2. Make sure that the RGC4 cryostat needle valve is fully opened (5 turns) in order to Circulation for maximize the helium circulation rate and cooling power.

  • Page 45: Making Experimental Measurements

    To prevent the RGC transfer line internal insulation from burning when the ST-400-800 K cryostat is cooled by an RGC4 system, it is important to keep some helium flow through the RGC recirculating system up to the 800 K set point. If the SuperTran cryostat heater...

  • Page 46: Warming The Continuous Flow Cryostat For Sample Exchange

    Cryostat After lower. Sample Exchange 2. Confirm that valves V1, V6, and V7 are open and the RGC4 cryostat needle valve is completely open (5 turns). 3. Begin helium circulation by slowly opening valve V9 while monitoring the return pressure on gauge G3. Open and close V9 repeatedly, so that the pressure on gauge G3 increases to the range of -2 inHg vacuum to 1 bar (0 inHg on gauge G3) over a period of approximately 5 min.

  • Page 47: Warming The System To Room Temperature

    To prevent damage to the CCR cold head, make sure the CCR first and second stage temperatures never exceed 300 K. The vacuum valve of the RGC4 cryostat and the continuous flow cryostat should never be opened to atmospheric pressure before all temperature sensors indicate room temperature (~290 K).
  • Page 48 CHAPTER 4: Operation Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 49: Chapter 5: Advanced Operation

    1. Warm the RGC4 cryostat to room temperature as instructed in section 4.13 of this manual. 2. When the RGC4 cryostat is at room temperature, use the evacuation valve to vent dry nitrogen gas into the vacuum space of the RGC4 cryostat.
  • Page 50 6. After removal of the radiation shield bottom cover, the connection between the RGC4 cryostat capillary and the transfer line capillary tube will be under the alu- minized mylar insulation (MLI) wrap. Carefully cut the tape from the aluminized mylar insulation (MLI) wrap and remove the MLI, setting it aside to be reinstalled later.
  • Page 51 On the exterior of the RGC4 cryostat, carefully support the transfer line and remove the vacuum clamp that joins the transfer line to the RGC4 cryostat. Carefully pull the transfer line and capillary tube away from and out of the RGC4 cryostat.

  • Page 52: System Assembly And Installation

    21. Clean and grease the o-ring, and install in the o-ring groove of the bottom cover of the vacuum shroud. 22. Install the bottom cover of the vacuum shroud to the RGC4 cryostat. Tighten the bolts of the bottom cover of the vacuum shroud securely.

  • Page 53: Cooldown

    ~ 50 C degrees during cooling to avoid the ice formation (see FIGURE 5-6). 6. Open valves V1, V3, V6, V7, and V9. Valves V2, V4, V5, and V8 should remain closed. 7. Make sure that the GHS circulation scroll pump is running. www.lakeshore.com...
  • Page 54 15. Open the cryostat needle valve approximately 7/8 turn. 16. After approximately 3-4 h, the STVP cryostat temperature should reach ~ 8 K to10 K, depending on the RGC4 model and STVP cryostat configuration. Initially, the temperature of the STVP cryostat will increase and then will start to decrease, which is normal.

  • Page 55: Temperature Control

    STVP cryostat. In this case, after the high temperature points are take, the needle valve should be reopened TO ~ 7/8 turn to reach the STVP cryo- stat base temperature. www.lakeshore.com...

  • Page 56: Stvp Cryostat Sample Changing

    Otherwise, air can enter into the sample tube, forming ice inside the sample tube. After warming up the sample positioner assembly to room temperature and chang- ing the sample, follow the procedure below. Model RGC4 Cryogen-Free Recirculating Gas Cooler...
  • Page 57 If valve V5 is opened to quickly, a big helium flow can overheat the trap located on the cold head first stage, and the circulation system can be blocked. e. After the temperature of the sample positioner reaches ~ 15 K, follow steps 13-17 in section 5.3.2 to get the base temperature of the STVP cryostat. www.lakeshore.com...
  • Page 58 CHAPTER 5: Advanced Operation Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 59: Chapter 6: Maintenance And Troubleshooting

    Chapter 6: Maintenance and Troubleshooting 6.1 General This chapter describes maintenance requirements for the RGC4 system, including both preventive maintenance schedule and maintenance instructions. 6.2 Maintenance This section includes both a preventive maintenance schedule and maintenance instructions, unless those instructions are included elsewhere in this manual.

  • Page 60: Recirculating Scroll Pump Exhaust Filter Replacement

    The moving parts within the CCR cold head require service after approximately 10,000 hours of operation (or 20,000 hours of operation for pulse tube cold heads). Maintenance Contact Lake Shore or your local representative to schedule this service. Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 61: Zeolite Trap: Regeneration (If Equipped)

    8. Inspect the seal in the knurled cap and replace if necessary. Reinstall the knurled cap and tighten. 9. Follow the Zeolite Regeneration procedure in section 6.2.5. 10. The system can now be returned to service. www.lakeshore.com...

  • Page 62: Gas Handling System (Ghs) Circulating Scroll Pump

    6.2.7 Gas Handling The GHS circulating scroll pump includes replaceable tip seals that wear with use. As the tip seals wear, pump performance degrades, resulting in poor RGC4 system System (GHS) operation. The tip seals should be replaced when the pump no longer performs...

  • Page 63: Charging The Ccr Compressor With Helium Gas

    Charge the CCR compressor helium gas if the pressure indication on the supply pressure is lower than the value specified in the operating manual. Refer to the Compressor with compressor operation manual for specific instructions on charging the helium gas. Helium Gas www.lakeshore.com...

  • Page 64: Wiring Diagram

    6: Maintenance and Troubleshooting HAPTER 6.3 Wiring The wiring diagram for the 19-pin feedthrough for the Lake Shore Model RGC4 cryostat is shown below. Diagram Maximum temperature is 300 K. FIGURE 6-4 Wiring diagram Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 65: Troubleshooting

    (see section 4.13) and then purged, following section 4.7 of this manual. Condensation on the outside If these symptoms appear, the RGC4 cryostat vacuum level of the RGC4 cryostat vac- may have decayed. Re-evacuate the cryostat vacuum shroud uum jacket and/or inability as described in the cryostat evacuation section 4.5.
  • Page 66 ALWAYS used with the second stage temperature sensor. Damage may result to the cold head if the first and second stage temperature sensors and heaters are interchanged. Model RGC4 Cryogen-Free Recirculating Gas Cooler...

  • Page 67: Technical Inquiries

    Contact Lake Shore Technical Support through any of the means listed below. However, the most direct and efficient means of contacting is to complete the online service request form at https://www.lakeshore.com/support/. Provide a detailed description of the problem and the required contact information. You will receive a response within 24 hours or the next business day in the event of weekends or holidays.

  • Page 68: Shipping Charges

    Replacement or repaired parts, or a replaced product, will be warranted for only the unexpired portion of the original warranty or 90 days (whichever is greater). 6.5.5 Restocking Fee Lake Shore reserves the right to charge a restocking fee for items returned for exchange or reimbursement. Model RGC4 Cryogen-Free Recirculating Gas Cooler...

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