Sun Power CryoTel MT User manual

CryoTel
TM Family
Free-Piston Stirling Cryocoolers
OPERATING INSTRUCTIONS
Model : CryoTel M T
Version 4
Issued: March 25, 2010

Sunpo wer Inc. CryoTel MT Operating Instructions version 4
SUNPOWER
®
Athens, OH 45701 USA
www.sunpower.com
Manufactured by Sunpower, Inc., under the following patents: U.S. Pats 4,583,364; 4,602,174; 4,623,808; 4,649,283;
4,805,408; 4,864,232; 4,866,378; 4,912,409; 4,926,123; 5,003,777; 5,148,066; 5,342,1 76; 5,385,021; 5,450,521;
5,457,956; 5,461,859; 5,496,153; 5,502,968; 5,525,845; 5,537,820; 5,592,073; 5,642,088; 5,642,622; 5,715,693;
5,749,226; 5,775,273; 5,873,246; 5,941,079; 6,035,637; 6,038,874; 6,170,442; 6,199,381; 6,293,184; 6,446,336 B1;
6,536,3 26; 6,684,637; RE 38,337; 6,782,700; U.S. patents pending. Also: Australia Patents 676,805; 677,518; 680,770;
685,997; 701,785; 709,315; 753,580;754032. Brazil PI 950368 - 5; PI 960 8885 - 0; PI 9710742 - 5; PI 9713840 - 1; PI
9713840 - 1. Canada patent 2,184,4 73. EPO 0655120 1B issued in France, Italy, UK, Netherlands, Sweden and
Germany (as DE 69329862.6 - 08). EPO 0693160 issued in Italy, UK, Netherlands France, Germany (as DE 69403468
T2); EPO 0754364 1B issued in France, Italy, UK, Netherlands and Germany ( as DE 69526217.3 - 08). EPO 0783618 1B
issued in France, Italy, UK, Netherlands and Germany (as DE 69518926.3 - 08). EPO 0878014 1B issued in France, Italy,
UK, Netherlands and Germany (as DE 69611387.2 -08). EPO 0885413 1B issued in France, Italy, UK, Nether lands and
Germany (as DE 69627894.4 - 08). Italy 1297082. UK Patent No. 0,218,682; UK 2,334,307; UK 2,330,651. DBP No.
0,218,682 (Germany).
India Patents 177477, 178274, 185034; 185035. Republic of Korea patents 0202290; 0292453; 0301548; 0309486;
032009 3. Mexico patents 184451; 194065; 197407; 201368. New Zealand Patents No. 263331; 282959; 319499;
302849; 517329. Singapore Patent P - No. 48360; 51842; 87422; 87423; 87424. Taiwan patent NI - 77875.
Japan Patents
Patents pending in United Kingdom, Germany, Italy, France, Netherlands, Sweden, Brazil, Japan, Republic of Korea,
India, China, Singapore.
Intellectual Property Declaration

Sunpower Inc. CryoTel MT Operating Instructions version 4
Sunpower, the Sunpower graphic identifier, and CryoTel are trade marks of Sunpower, Inc. and
are registered in the U.S. and other countries. Other products, logos, and Company names
mentioned herein may be trademarks of their respective owners.

Sunpo wer Inc. CryoTel MT Operating Instructions version 4
Table of Contents
I. Introduction .5
II. Precaution s (Dos and Don ts) .6
III. Unpacking 7
IV. Mechanical Mounting . 8
V. Attachment of Heat Load to Cold Finger .8
VI. Cold End Vacuum ...9
VII. Feedthroughs . . 10
VIII. Temperature Sensor 11
IX. Heat Rejection .13
A. Water Jacke t ..13
B. Copper Fins .. 14
C. Conducting Solid .. 14
X. CryoTel Operation . 15
A. Preparati on 15
B. Beginning Oper ation .15
C. Operation Shu tdown . 17
XI. LED and 5 Pin Connector S ummary .. .. 18
XII. CryoTel Serial Communications Command Reference . 20
A. Serial Interface Specifications . . 20
B. Controller Connector Wiring Information 20
C. CryoTel MT Terminal Emulator Commands 20
D. Remote On - Off con trol.... . 21
E . Allowable Number Form ats .. 22

Sunpower Inc. CryoTel MT Operating Instructions version 4 3
FIGURES
Figure 1: CryoTel M T ... . 5
Figure 2: CryoTe l Cryocooler .. ... 7
Figure 3: Pressure Vessel Mounting Holes . 8
Figure 4: Weld Flange holes 8
Figure 5: Cold Tip M3 Mounting Holes . 9
Figure 6: Power Cable . 10
Figure 7: Rear Pressure Vessel End Plate 11
Figure 8 : Temperature Sensor and W iring Harness . 11
Figure 9 : Test Cap Ass embly 12
Figure 10 : Controller Temperature Sensor Connector .. 13
Figure 11 : Water Jacket Heat Rejection 14
F igure 12 : Cooling Fin Heat Rejection 14
Figure 13: CryoTel M T Contro l Board .16
Figure 14: Controller LED s and 5 pin Connector .18
Figure 15: Optocoupler Circuit ..18

Sunpower Inc. CryoTel MT Operating Instructions version 4 4
This pa ge intentionally left blank.

Sunpower Inc. CryoTel MT Operating Instructions version 4 5
I. Introduction
Sunpower, Inc. is pleased to present this manual with your newly- purchased CryoTel model
cryocooler. As the world leader in free - piston Stirling cryocooling, Sunpower fully supports its
products and is pl eased to hear of any comments or concerns from new or existing clients.
CryoTel
TM
M T Operating Instructions
The Sunpower cryocooler is a precision instrument; robust in many ways but fragile in others.
This operating manual provides standard - use instruct ions and precautions. Please post where
technicians will be working with the unit. Please do not assume that if a warning or instruction
is not included here, a particular test or application of this unit is acceptable. It may not be. If
you have any q uestions about this unit, or about any tests or applications you intend to perform,
please contact Sunpower support service at phone (740) -594- 2221;
email cryo - [email protected]
Figure 1 : CryoT el MT
CryoTel MT dimensions:
length with balancer: 223 mm (8.9 in); length without balancer: 183 mm (7.2 in); diameter:
73 mm (2.9 in);
mass: 1.95 kg

Sunpower Inc. CryoTel MT Operating Instructions version 4 6
II. Precautions (Dos and Don ts)
Although the CryoTel M T is mechanically robust, it can be damaged if not handled properly
when in operation or when removing it from its packaging. The handling and operational Dos
and Don ts are listed below. Re fer to the diagram of the CryoTel MT in Figure 2.
CRITICAL! Do not operate the cryocooler without adequate cooling at the heat
rejection site. Overheating the cryocooler will cause permanent damage.
DON T
1. Pick up the cryocooler by the cold finger
2. Set the cryocooler on the cold tip.
3. Allow the cold finger to be dented. The slightest dent will render the unit inoperable.
4. Drill holes, or in any other way puncture, or attempt to modify, the pressure vessel.
5. Operate the unit without proper cooling. Heat must be removed from the copper heat
rejection area of the cryocooler. If the cooler is provided with external cooling fins, air must
be forced over the fins and the flow path should not be obstructed.
6. Puncture or otherwise damage the copper service tube.
7. Subj ect the electrical feedthroughs to mechanical stress; i.e. axial or radial movements,
axial loads, blows, or the like.
8. Mount the cooler by suspending it from the balance absorber mounting bolt.
9. Apply clamping pressure to the pressure vessel (labeled in Fig ure 2) .
10. Rigidly attach the absorber stud to ground. Instead, let the cooler float via a rubber
bushing or other means of articulation.
11. Remove the protective cover on the cold weld on the end of the copper charge tube. Do not
subject the cover to blow s.
12. Control power to the cryocooler by making or breaking the power leads between the
controller and the cryocooler.
13. Use an external, automatic, closed loop control system which attempts to control the
cryocooler operation by varying the setpoint settings in the cryocooler controller.
DO
1. Check with Sunpower before making any modifications to the cryocooler
2. Note that if the control board is installed in an enclosure, cooling must be provided.
3. If the cooler is operating in a laboratory test mode with heaters providing the thermal
load to the cold tip, interlocks should be provided so that the heater cannot operate
unless the cryocooler is running. This will prevent accidental overheating of the cold
tip.

Sunpower Inc. CryoTel MT Operating Instructions version 4 7
Figure 2 : CryoTel
TM
Cryocooler
II I . Unpacking
When unpacking or handling, only hold the cryocooler by the pressure vessel or the transition
(see Figure 2). Do not hold or support the cryocooler by holding the cold finger. The
CryoTel
TM
M T may sit horizontally on a level bench top or table, but the cooler must be
supported to prohibit rolling. The cold finger must be prot ected from any contact as well. The
cold finger is delicate. Any deformation of the cold finger, such as small dents, bending, etc.
will ruin the cryocooler.
In End
Out End
Vibration Absorber
Pressure Vessel
Mounting Holes
Transition
Service Tube Feedthroughs
Heat Rejection
Cold Finger
Cold Tip

Sunpower Inc. CryoTel MT Operating Instructions version 4 8
IV . Mechanical Mou nting
The CryoTel
TM
MT has a thick metal end plate on the out end of the pressure vessel nearest
the passive vibration absorber. M4 threaded holes on the outer diameter of the transition and
end plate are designed for attachment of the cooler to an exter nal mechanical structure for
testing or integration into the application. These can be seen in Figure 3.
On the face of the external copper ring that rejects heat from the cooler is a stainless steel plate.
The plate has four M3 threaded holes that can b e used for attaching a removable NW50 or
customer specified vacuum flange (see Figure 4). A vacuum flange can also be welded to this
plate , but must be done with a low energy weld such as plasma or micro TIG. It is
recommended that, if needed, the custom er allow Sunpower to perform the welding operation.
The mechanical structure including the cryostat attachment plate, heat rejection copper, and
transition have been designed to allow mounting the entire assembly by the cryostat and
cantilevering the cool er and vibration absorber from the cryostat in a given application.
V. Attachment of Heat Load to Cold Finger
The copper cold tip at the end of the cold finger has four M 3 threaded holes that can be used for
mounting equipment to the cold tip for applications or tests (see Figure 5). The application of
force to the cold tip must be handled with care and in accordance with these not - to - exceed
limits:
Cantilevered force, cooler not in operation: do not exceed a cantilevered force
on th e cold finger (static or shock) > 100 N (10.20kg).
Cantilevered force, cooler in operation: do not permit the heat load apparatus to
deliver force to the cold finger (static or shock) > 30 N (3.05 kg)
Vertical loading: do not exceed a pure tension or co mpression load > 300 N
(30.50 kg)
Torque , cold finger : do not exceed a load >16 N*m ( 142 in*lbs )
Threaded
Mounting
Holes
2 of 4 M3
Threaded
holes
Figure 3: Pressure Vessel Mounting Holes
Figure 4: Weld Flange Holes

Sunpower Inc. CryoTel MT Operating Instructions version 4 9
Figure 5: Cold Tip M 3 Threaded Holes
VI . Cold End Vacuum
The cold finger of the CryoTel
TM M
T operates best in an insulated vacuum. The vacuum
eliminate s possible loading of the cold finger from convection or condensation of elements in
the atmosphere such as water vapor and nitrogen. The vacuum is created by a customer
provided vacuum Dewar or cryostat. As noted above, a flange can connect the cryostat and the
stainless steel vacuum flange with an o- ring seal or welded attachment (Fig 2).
When using a mechanical vacuum pump it is appropriate to seal the flange with an o - ring and
clamp. The vacuum pump will remove any residual gasses released by the o - ring and continue
to maintain a vacuum inside the cryostat. However, an o -ring may corrode and become brittle
over an extended period of time.
For customer applications requiring long - term vacuum without using a vacuum pump, it is
recommended that the cr yostat be welded to the CryoTel vacuum interface.

Sunpower Inc. CryoTel MT Operating Instructions version 4
10
VI I . Feedthroughs
The electrical pins on the metal plate at the end of the pressure vessel near the balance absorber
are surrounded by glass, which acts as an insulator and prevents helium from leaking out of the
pressure vessel. This arrangement is called a feedthrough. Because of the glass insulator, the
feedthroughs should be handled cautiously. They are a permanent feature of the pressure
vessel back end plate and should not be modified in any way.
The CryoTel M T is shipped with a power cable that attaches to the feedthroughs and the
controller. This wiring harness consists of orange and white 16 gauge wires with a molded
plastic connector for the feedthroughs at one end and a plastic connector housing that plugs
directly into the controller output cable of the same wire colors. This harness is shown in
Figure 6.
Figure 6: Power Cable
It is necessary to remove the balance absorber in order to install the power cable. The balance
absorber is attached with the center M5 screw. Remove this screw and the balance absorber
will be free from the cryocooler.
Install the power cable by aligning the cryocooler feed through pins with the holes in the cable
connector and pressing down. Insert the retaining screw into the connector and tighten.
Install the balance absorber by re - installing the M5 s crew.
Important assembly notes :
The heads of the four screws that fasten the balance absorber assembly together
should be facing towards the cryocooler. The nuts for these screws will be on
the top of the balance absorber.
The screw heads of the four balance absorber assembly screws need to be
positioned so that none of them are directly over either the power cord connector
or the service tube elbow. This is to ensure that the screw head does not impact
either of these features during large amplitude displacements of the balance
absorber.

Sunpower Inc. CryoTel MT Operating Instructions version 4
11
Figure 7: Rear Pressure Vessel End Plate and Power Cable Wire Harness
VII I . Temperature Sensor
For proper operation of the CryoTel
TM
controller it is necessary to mount a temperature sensor
to the object being cooled. The sensor allows the controller to measure and control the cooled
object s temperature. The sensor feedback also controls the cooler s power ramp - up. If the
sensor is not installed properly, the cooling capacity of the cryocooler will be severely limited
and temperature control will not function.
The controller sensor may be either a PT -111 platinum RTD or equivalent. Sunpower
packag es the PT - 111 in a copper disk so that the sensors are identical in s ize, shape and wiring.
Figure 8 shows the sensor and the wiring harness connecting sensor to controller.
Figure 8 : Temperature Sensor and Wiring Harness
The temperature sensor is e ncased in a small copper slug. Use an M3 screw in the 3mm drilled
hole to attach the sensor to the test cap or to the object being cooled. Use a thin layer of
Temperature
Sensor
Wiring
Harness
Service
Tube
Pressure
Vessel
-
Feedthrough
+
Feedthrough
Service Tube Elbow
Power
Cable

Sunpower Inc. CryoTel MT Operating Instructions version 4
12
Indium, Apiezon grease, or similar thermal grease between the sensor and the object to insure
proper thermal conduction.
Laboratory testing can be accomplished with a test cap arrangement similar to the one shown in
Fig 9 . The test cap consists of a copper disk, two resistors, two through holes with M 3
clearance for connection to copper tip, and two M3 holes for attachment of sensors to the test
cap. Calculate the heat load (power in Watts = current x voltage) by providing a known voltage
and current across the resistors on the test cap. Mount the control sensor using one of the M3
mounting hol es on the test cap. If using a second sensor, mount it to the test cap for
independent temperature measurement. Apply an appropriate thermal grease to the bottom face
of the test cap in order to maximize conduction. Mount the test cap to the cold tip us ing the M 3
threaded holes on the cold tip.
Figure 9 : Test Cap Assembly
When the cold tip is contained in a vacuum vessel, use feedthroughs to connect the wiring
harness to the sensor wires. Use at least four conductors connecting t he feedthrough to the
control temperature sensor. Use additional feedthroughs if employing a test cap or other
sensors inside the cryostat. All wires inside the cryostat should be as small as possible in order
to minimize parasitic loading on the cooler. The wires of the sensor and wiring harness are
color coded to help insure proper connection. Table 1 shows the proper co nnection of the
wires. Figure 10 and Table 2 describe proper connections of the wiring harness to the CryoTel
Controller.
Temperature
sensors
M4 Mounting
screws
Resistors
(heat load)

Sunpower Inc. CryoTel MT Operating Instructions version 4
13
RTD Wire Color Wiring Harness Color
Black Black
Red Red
Clear White
Green Green
Table 1
IX . Heat Rejection
Proper heat rejection is crucial to the operation of a cryocooler. Some CryoTel heat rejection
options are a water jacket, copper fins, or a conducting solid.
CRITICAL! Do not operate the cryocooler without adequate cooling at the heat
rejection site. Overheating the cryocooler will cause permanent damage.
A. Water Jacket
Sunpower can provide a permanent or removable water cooling j acket with the CryoTel M T
(Fig. 1 1 both are identical in appearance ). Use a suitable thermal grease to maximize
conduction between the heat rejector and the water jacket if using a removable unit (the
permanent unit is installed at the factory and does no t require thermal grease ). The thermal
grease should be refreshed periodically as it will dry out over time. After connecting the water
supply to the water jacket for heat rejection, ensure that air is removed from the water jacket.
This can be done by fl owing water through the cooling system for several minutes prior to the
run. If it appears that air is still trapped in the water jacket, try carefully tilting the cooler in the
direction away from the cooler discharge tube. This will raise the level of th e discharge tube
and allow any trapped air to escape. Trapped air will decrease heat rejection and cooler
performance. Water should be flowing through the jacket at approximately 5 mL per second
(0.08 gallons per minute).
Mating connector for temperature interface
cable is DigiKey part # WM2903.
Terminals are DigiKey part # WM2554.
RTD Harness
PIN Function W ire Color Wire Color
1 I+ White (Clear) White
2 I- Red Red
3 V+ Black Black
4 V- Green Green
5 Shield
Table 2
Pin 1
marked by
triangle
Figure 10 : Controller Temperature Sensor Connector

Sunpower Inc. CryoTel MT Operating Instructions version 4
14
Figure 1 1 : Water Jacket Heat Re jection
B. Copper Fins
Copper fins are also available in a permanent or removable form. If copper fins are used for
heat rejection (Fig. 12 - permanent fins are pictured ), use a fan with a rating of 100 cubic feet
per minute (1.6e - 3 m
3
/min) for air throug h- flow. Sunpower recommends mounting the fan to a
cylindrical shroud that can be placed around the fins in order to direct the air through the fins.
Note that some heat rejection also occurs from the walls of the pressure vessel. Therefore avoid
permittin g any containment structure for the cryocooler to hinder the heat rejection from any
part of the cooler. It is also recommended to electrically interlock the cooling fan and the
controller in order to ensure that the cooler cannot operate without also turn ing on the fan. For
additional cost, Sunpower is able to provide a fan, shroud, and controller that are suitable for
laboratory testing.
Figure 12 : Cooling Fin Heat Rejection
C. Conducting Solid
Use of any other means of heat rejection necessitates en suring that the proper amount of heat is
being transferred away from the rejector and that the reject temperature is suitable. It is
recommended to involve Sunpower with the design of a conduction heat exchanger.

Sunpower Inc. CryoTel MT Operating Instructions version 4
15
X. CryoTel Operation
CRITICAL! Do no t operate the cryocooler without adequate cooling at the heat
rejection site. Overheating the cryocooler will cause permanent damage.
A. Preparation
1. Attach application apparatus or test cap to cold tip of cold finger.
a. Apply a thin layer of Apiezon therm al grease or Indium to the copper tip of the cold
finger in order to maximize conductivity.
2. Attach the customer - provided cryostat by appropriate means if a vacuum is required for the
application.
3. If using a vacuum, make wire connections from temperature se nsor and any other
measuring devices inside the cryostat through Dewar feedthroughs.
a. For maximum performance, wires should not touch the walls of the Dewar. Contact
with walls will increase the heat loading (conduction) during use and will yield
lower ava ilable cooling power.
4. Seal the cryostat vacuum except for the connection to the vacuum pump (if using vacuum).
5. Mechanically attach the cryocooler assembly to the customer provided mounting device.
6. Connect the wiring from the cryostat feedthroughs to the ap propriate test and measurement
devices.
a. The cold tip temperature sensor must be connected to the controller s mating
connector as described previously using the provided wiring harness and connector
(See Figure 1 3 for controller connections).
7. Attach the va cuum pump to cryostat, start the vacuum and allow it to reach a vacuum of
10
-4
Torr or better.
B. Beginning Operation
1. Prepare the CryoTel M T for testing as described above.
2. Connect the power cables for the CryoTel MT to the controller s mating connector
(c ontroller connections in Fig. 13 ).
a. Verify the correct polarity is observed with respect to the CryoTel M T orange
power cable wires are positive, white wires are negative.
b. Attach the included wire harness to the cooler as shown in Figure 6 then attach t he
plastic connector at the other end to the connector with orange and white wires on
the controller (Fig 13).
i. Note: The connector attached to the cooler wires is an AMP Mate -N- Lok®
plug housing, 1-480698- 0; with AMP Mate -N- Lok® contacts, 3505471 - 1(
avail able from Mouser Electronics, part numbers 571 - 14806980 and 571 -
3505471 respectively).
ii. Note: The connector attached to the controller wires is an AMP Mate-N-
Lok® cap housing, 1 - 480699 -0 with AMP Mate-N- Lok® contacts, 350550 -
1 ( available from Mouser Electr onics, part numbers 571 - 14806990 and 571 -
3505501 respectively).
3. Connect the controller to a 24V
DC
power outlet.
a. Note: The input power connector attached to the control board is an AMP Mate -N-
Lok® cap housing, 1 - 480699 -0 with AMP Mate-N- Lok® contacts, 350547 - 1 (

Sunpower Inc. CryoTel MT Operating Instructions version 4
16
available from Mouser Electronics, part numbers 571 - 14806990 and 571 -3505501
respectively).
b. Note: Use a suitable connector for the power supply such as the same AMP Mate -
N- Lok® plug housing used for the cryocooler power cables, AMP part number 1 -
480698-0 with AMP universal connector socket, 350550-1.
c. The controller has a startup sequence that positions the piston in the axial center.
This sequence takes approximately 7- 10 seconds once the controller is turned on.
d. The controller then applies a 60 Hz AC voltage to the motor, creating the oscillating
motion of the piston that begins the cooling process.
e. The controller increases the power input to the cryocooler based on cold end
temperature and predetermined time constants. The maximum draw by the
con troller is approximately 1 00 W
E.
4. Allow cold tip temperature to stabilize at desired cold end temperature
a. Proper operation of the CryoTel M T requires a minimum loading of 2 Watts. If
minimum load requirements are not met, the stabilized temperature will be below 77
K.
Figure 13 : CryoTel M T Control Board
+24V
Positive (red lead)
input is fused
Temperat ure
sensor
Serial
Communications
Connector
Output Power
Orange wire to +
Motor Terminal
15 Am p fuse

Sunpower Inc. CryoTel MT Operating Instructions version 4
17
C. Operation Shutdown
1. Turn off the controller.
a. The quick rattle heard when power is cut off from the CryoTel is due to the stored
energy in the vibration absorber being dissipated.
b. In rare cases where the operating temperature was below 60 K, it has been observed
that the cooler can energize itself during shutdown and become an engine. To
prevent this, allow the cold tip to reach a temperature above 60 K before shutting
down.
2. Allow th e cold tip and the rest of the cryocooler temperature to rise to room temperature
before opening the vacuum in order to prevent the vapor outside the cryostat from
condensing and freezing on the cold tip.
a. Applying a heat load to the cold tip during the war ming process reduces the time
needed to reach room temperature.
b. Sunpower recommends using a relay in conjunction with the temperature sensor to
ensure that the power supply to the heat load shuts off when the cold tip temperature
reaches 300 K.

Sunpower Inc. CryoTel MT Operating Instructions version 4
18
XI . LED an d 5 Pin Connector Summary
The two LED s, shown in figure 13 , indicate whether the cooler has reached its set point
temperature or if the cooler is still in cool down mode. The red LED will be on as long as th e
cooler is in cool down mode. When the cooler reaches its set point temperature within 0.5K the
green LED will turn on.
The 5-pin connector is connected to an optocoupler circuit as shown in Figure 15. When the
green LED is on, current is able to flow from pin 1 to pin 5 through the Darlington
Phototransistor. When the green LED is off, the current flow through the phototransistor is
blocked. This would be useful if the user wanted switch an externally powered indicator light
or control system input on when the cooler reaches the set point temperature. Pins 2, 3, and 4
on the 5 pin connector are not used .
Figure 1 4: Controller LED s and 5 pin Connector
Figure 15: Optocoupler Circuit.
Phototransistor is on when green L ED is on.
PIN 1 P IN 5
Red LED
Green LED
5 pin connector
L
ED
s
LED
PIN 1
PIN 5
Darlington
Phototransistor
(MOCD223)