Toward understanding the fundamental mechanisms and properties of the thermal mass flow controller

Hinkle, L. D.; Mariano, Chiara

doi:10.1116/1.577452

Cited by 31 publications

(11 citation statements)

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“…Commercial MFCs are routinely used to measure and control the mass flow rate of gases into vacuum environments in industries ranging from semiconductor manufacturing to aerospace design and testing [17]. In EP applications, MFCs are often integrated into the propellant feed system and used to regulate the mass flow rate of propellant gas to the propellant distributor and external thermionic cathode [18].…”

Section: Fundamentals Of Laboratory Measurement Devicesmentioning

confidence: 99%

“…There are two basic methods of flow rate control employed in modern MFCs: thermal mass flow control (TMFC) and pressurebased mass flow control (PMFC) [17,19]. Thermal control relies on the transfer of heat from an electrically heated wall to a moving fluid.…”

Section: Fundamentals Of Laboratory Measurement Devicesmentioning

confidence: 99%

“…The first is the gas flow region shown in the bottom of the figure, which consists of the inlet, turbulence filter, capillary bypass/flow sensor, valve, and outlet. As process gases enter the TMFC, a laminar flow restriction, shown in the figure as a decrease in the flow crosssectional area, diverts a small percentage of gas through a capillary bypass tube to a thermal flow sensor and then back to the main flow region [17,21]. Note that the exact design of the thermal flow sensor and bypass differs between manufacturers.…”

Section: A Thermal Mass Flow Controllers 1 Working Principles and Omentioning

confidence: 99%

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Recommended Practice for Flow Control and Measurement in Electric Propulsion Testing

Snyder

Baldwin

Frieman

et al. 2017

Journal of Propulsion and Power

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Accurate control and measurement of propellant flow to a thruster is one of the most basic and fundamental requirements for operation of electric propulsion systems, whether they be in the laboratory or on flight spacecraft. Hence, it is important for the electric propulsion community to have a common understanding of typical methods for flow control and measurement. This paper addresses the topic of propellant flow primarily for the gaseous propellant systems that have dominated laboratory research and flight application over the last few decades, although other types of systems are also briefly discussed. Although most flight systems have employed a type of pressure-fed flow restrictor for flow control, both thermal-based and pressure-based mass flow controllers are routinely used in laboratories. Fundamentals and theory of operation of these types of controllers are presented, along with sources of uncertainty associated with their use. Methods of calibration and recommendations for calibration processes are presented. Finally, details of uncertainty calculations are presented for some common calibration methods and for the linear fits to calibration data that are commonly used.

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Section: Fundamentals Of Laboratory Measurement Devicesmentioning

confidence: 99%

Section: Fundamentals Of Laboratory Measurement Devicesmentioning

confidence: 99%

Section: A Thermal Mass Flow Controllers 1 Working Principles and Omentioning

confidence: 99%

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Recommended Practice for Flow Control and Measurement in Electric Propulsion Testing

Snyder

Baldwin

Frieman

et al. 2017

Journal of Propulsion and Power

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“…The thermal flow sensor works on the principle of heating and cooling a temperature sensor (usually a wound metallic element), and the flow sensor's response time is a function of both the heat capacity of the temperature sensor and the quality of its thermal communication with the gas. For ultra-high-purity (UHP) applications, where the gas cannot be in direct contact with the temperature sensor, the response time is on the order of 1 sec [4]. This represents an inherent limit to the response time for thermal-based MFCs.…”

Section: Introductionmentioning

confidence: 99%

A new device for highly accurate gas flow control with extremely fast response times

Boyd

Monkowski

Ding

et al. 2011

2011 IEEE/SEMI Advanced Semiconductor Manufacturing Conference

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This paper presents a new type of control scheme and device for controlling gas flow into semiconductor process chambers. The key component of the Gas Flow Controller (GFC) is a high-precision valve with an integrated position sensor, which is used to maintain a constant flow rate. A map lookup scheme is employed to adjust the valve position to accommodate the upstream pressure, including any changes or disturbances. The layout of the flow controller also allows for the incorporation of a pressure-volume-time-temperature-based flow measurement, which is a primary standard flow measurement, to confirm and maintain flow accuracy throughout the device's lifetime. The fast response time of the sensors and the high sampling rate in the control loop enables the control of the gas flow within the order of tens of milliseconds.

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“…The precise control of flow in the process warrants minimal error in the measuring instruments. Improved performance, low cost, low-pressure drop, compactness in size and a small response time have helped thermal mass flow meter (TMFM) gain acceptance in the industry for gas flow measurements [1][2][3]. Thermal mass flow meters are widely used in measuring gas flows with applications to semiconductor manufacturing gas distribution, heating, ventilation, air-conditioning, human inhalation system, environmental safety, etc.…”

Section: Introductionmentioning

confidence: 99%

Understanding the Compatibility of Thermal Mass Flow Meter with Various Process Gases

GN¹,

Mahendra²

2011

J Chem Eng Process Technol

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A majority of vacuum processes use the Thermal Mass Flow Meter (TMFM) as metering device for process gas. The purpose of this paper is to establish cross compatibility relationship of the TMFM with different process gases. This paper uses a compressible Computational Fluid Dynamic (CFD) solver to understand the behavior of TMFM with different process gases. The change in the characteristic curve at lower pressures has also been studied. Empirical correlations have been developed so that the change in characteristic curve of TMFM can be predicted accurately for different gases based on their physical properties.

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Toward understanding the fundamental mechanisms and properties of the thermal mass flow controller

Cited by 31 publications

References 0 publications

Recommended Practice for Flow Control and Measurement in Electric Propulsion Testing

Recommended Practice for Flow Control and Measurement in Electric Propulsion Testing

A new device for highly accurate gas flow control with extremely fast response times

Understanding the Compatibility of Thermal Mass Flow Meter with Various Process Gases

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