Building on the success of the Mark 20, we have continued to improve the design with the Mark 26.  The most noticeable difference is the way the MK26 is mounted.  The MK26 is equipped with a solid copper mounting flange.  This new flange simplifies mounting and provides excellent thermal conductivity.  All TQCMs are designed to utilize a heatsink or mounting flange that will remain near ambient temperature.  A cable connector has been added to the rear for convenience.  An in-situ peltier and temperature sensor provide controllable heating and cooling capabilities to bring the temperature of the crystals to a temperature at which a gas of interest will condense on the crystal so that it can be measured.

The MK26 can be purchased with custom crystal frequencies to enhance mass measurements or sensitivity measurements down to the mono-molecular level.

The MK26 features a Peltier (thermoelectrically-controlled) heat exchanger which is used to raise or lower the temperature of the crystals.  This feature is useful for outgassing tests at low temperatures without supplying any refrigerant.  Also, by actively cooling the heat sink, the lowest temperature attainable by the crystal is further reduced.  The differential temperature that was available at ambient temperatures is reduced by the Joule heating effect, which cancels out the cooling capacity.

The MK26 has four design configurations:

• The MK26-1  is the standard unit, which utilizes the two-stage Peltier, operating at a temperature range of -60 °C to 80°C with 6.25 watts maximum power required for crystal temperature control, and has a customer selected option of 10 or 15 MHz crystal configuration.
• The MK26-2 Sub-Micron unit has similar temperature characteristics to the MK26-1, but uses mini-crystals, to enhance sensitivity over mass measurement.  The recommended customer selected crystal frequencies are 15, 25, and 50MHz.
• The MK26-3 Low Power unit With a single-stage Peltier, it has a slightly lower profile and measures only 0.722″ in height.  It has a temperature range of -38°C to 80°C with lower power requirements of 3.2 watts for crystal temperature control.  The -3 has recommended options of 10 or 15 MHz crystal frequencies.
• The MK26-4 Extended Frequency / Temperature Range utilizes a three-stage Peltier with a 4.4 watt maximum power requirement and an extended temperature range of -80°C to 80°C.  It uses the mini-crystals with recommended customer selected crystal frequencies of 15, 25, and 50MHz.

When used in a vacuum chamber, the MK26 TQCM is used with a QCM Research Model 2000 Control/Data Acquisition Unit.  The M2000 is able to handle up to twelve MK26 TQCMs at one time, and communicates with a host computer over an industry standard RS 232 serial link.

When used in flight, the MK26 TQCM is controlled with a QCM Research Model 3000 Flight Controller.  The M3000 is modular in design and can control two QCMs per module, with up four modules per M3000 providing eight QCM channels.

The Mark 24 Thermoelectric Quartz Crystal Microbalance (MK24 TQCM) is a breakthrough in miniaturization. It is the smallest and lightest TQCM in our product line. This QCM is rugged in design, built to withstand shock, vibration and varying temperatures from -25°C to +80°C when active and -199°C to 100°C when the peltier heat exchanger is not in use. Weighing in at less than 4.5 grams and requiring only 1.54 Watts of peak power, the MK24 is “in step” with aerospace budget demands to reduce payload, scale, and power consumption.

Each MK24 has an internal, single stage, thermoelectric peltier heating and cooling element. When used in conjunction with an internal temperature sensor, it allows accurate remote control of the crystal temperature. The crystal temperature can be adjusted to where gasses condense on the crystal, and the increased mass of the condensation changes the frequency of the crystal in a linear mass-to-frequency relationship. QCMs can be extremely sensitive down to the monomolecular level. By adjusting the temperature of the crystals to specific condensation temperatures, one can look for various gasses and contaminates as they condense and then they can be boiled off to prepare for another measurement.

MK24s have also been used in a reverse procedure where the crystals have been coated with various substances. The MK24 has then been tested in Low Earth Orbit to determine the erosion rate of the substance. Material laboratories use TQCMs in the investigation of vacuum outgassing of spacecraft materials in space simulation vacuum chambers.

MK24 TQCMs can be flight approved and have flight history. Custom orders are common and welcome. Call to discuss how we can build a MK24 TQCM system to meet your needs.

The MK20 TQCM is a proven flight performer, and has been a popular model for commercial use in vacuum chambers. If you are interested in the MK20 also take a look at its successor, the MK26. All MK 20s come standard with a peltier heat exchanger providing both heating and cooling to the crystals and a temperature sensor to report the current crystal temperature. The MK20s are customizable to your application, having three MK20 models to choose from:

The MK20 has three design configurations:

The MK20-1 is our Standard unit and has a distinguished flight history. It requires 6.35 watts peak power and 100mW when the peltier is not in use. The operating temperature range is from -60°C to 80°C and has a customer selected option of a 10 or 15 MHz crystal configuration.
The MK20-2 is the Sub-Micron unit which utilizes smaller diameter and higher frequency crystals, up to 50MHz. This allows the measurement of contamination down to 0.02 monolayer / Hz. It requires 6.35 maximum watts of power. The temperature range is from -60°C to 80°C.

The MK20-3 is our Low Power Peltier unit. The low power model is ideal for flight use. It uses only 3.3W peak. This is particularly useful for integration into power-limited spacecraft if a somewhat reduced temperature range of ∆T=58°C can be tolerated. The temperature range is from -38°C to 80 °C.
When used in a vacuum chamber, the MK20 TQCM is used with a QCM Research Model 2000 Control/Data Acquisition Unit. The M2000 is able to handle up to twelve MK20 TQCMs at one time, and communicates with a host computer over an industry standard RS 232 serial link.

When used in flight, the MK20 TQCM is teamed with a QCM Research Model 3000 Flight Controller. The M3000 is modular in design and can control two QCMs per module. The modules can be stacked up to four modules or eight QCM channels or can be spread out around the spacecraft.

Selecting from available crystal frequencies can further enhance sensitivity or mass measurements. MK20 TQCMs can be flight approved and have flight history. We often custom build MK20s to the customer’s needs. Call to discuss how we can build a MK20 TQCM System for you.

The Mark 10 Thermoelectric Quartz Crystal Microbalance (MK10 TQCM) has become the defacto industry standard TQCM.   By cooling the 10 or 15 MHz quartz crystals, measurements can be made of the mass flow as it intercepts and is condensed at a specific temperature.  For space applications, the Sunwise crystal option has been added to minimize the solar thermal radiation input on the crystals.

The MK10 can be cooled by its own in-situ thermoelectric Peltier element without any external refrigerant, with a delta T of > 70°C when the heat sink is at ambient temperature.  This feature makes it particularly useful for material laboratories in the investigation of vacuum outgassing of spacecraft materials.   Monolayers of contamination are quite easily seen.   Additionally, a flight MK10 placed on a satellite will assure that the sensor crystal temperature for condensation of the particular contaminates will be obtained.   Two MK10 sensors have been supplied, for example, for measuring the backflow of gasses onto a satellite from an ion rocket exhaust.

Baking the QCM at 40° to 50°C eliminates the accumulated contaminants.  The technique of slowly raising the temperature can be used for selectively identifying all of the fractionations that may be condensed.  If the MK10 is actually cooled externally at its heat sink plane of attachment, the lowest temperature at which it can operate is extended to approximately -200°C.

MK10 TQCMs can be flight approved and have a successful flight history.  Custom orders are common and welcome.  Call to discuss how we can build a MK10 TQCM system to meet your needs.