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Asked: October 24, 2023In:
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What are the four basic rules for working under HV and UHV conditions?

high vacuumultra-high vacuum
  1. VacuumFurnaces.com Answers

    When working with high vacuum (HV) and ultra-high vacuum (UHV), there are specific aspects to consider ensuring an efficient and safe system. To clarify, the pressure range of UHV conditions are defined as between 10-7 and 10-12 mbar, whereas HV conditions are defined as between 10-3 and 10-7 mbar.Read more

    When working with high vacuum (HV) and ultra-high vacuum (UHV), there are specific aspects to consider ensuring an efficient and safe system.

    To clarify, the pressure range of UHV conditions are defined as between 10-7 and 10-12 mbar, whereas HV conditions are defined as between 10-3 and 10-7 mbar. Some of the main applications of HV include metallurgical processes, nuclear physics, space simulation and analytical instruments. On the other hand, UHVs are used for surface analysis, in high-energy physics and Molecular Beam Epitaxy (MBE).

    Here are the four main considerations you need to bear in mind when working under HV or UHV conditions.

    1. Vacuum systems design, materials, and surfaces.
    2. Managing working conditions and cleanliness.
    3. Choosing the right pump technology.
    4. Conductance influence.

    Source: Vacuum Science World – Four basic rules for working under HV and UHV conditions.

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Asked: October 24, 2023In:
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What are some of the main questions to ask when selecting a vacuum gauge?

vacuum gauges
  1. VacuumFurnaces.com Answers

    When considering the purchase of a vacuum gauge, here are some of the basic questions to ask yourself: What pressure range are you looking for? What accuracy range are you seeking? Are there any other ranges that are important? Do you need to control or regulate, in addition to measuring? What formRead more

    When considering the purchase of a vacuum gauge, here are some of the basic questions to ask yourself:

    1. What pressure range are you looking for?
    2. What accuracy range are you seeking?
    3. Are there any other ranges that are important?
    4. Do you need to control or regulate, in addition to measuring?
    5. What form (panel mounted or desktop) gauge are you looking for?
    6. What kind of power do you have/need?

    Source: Vacuum Gauges – VAC AERO International

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Asked: October 22, 2023In:
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In any heat treating cycle, what are the main considerations concerning temperature?

workload temperature
  1. VacuumFurnaces.com Answers
    This answer was edited.

    In any heat treating cycle, there are two important considerations concerning temperature: the temperature of the furnace hot zone which is generating the heat input, and the temperature of the actual workload. Heating by direct radiation, the main heating mechanism in vacuum, tends to be a slower pRead more

    In any heat treating cycle, there are two important considerations concerning temperature: the temperature of the furnace hot zone which is generating the heat input, and the temperature of the actual workload.

    Heating by direct radiation, the main heating mechanism in vacuum, tends to be a slower process than other heating mechanisms such as convection or conduction. As a result, there are times in the heat treating cycle, particularly during heat up, when the load will be at a lower temperature than the furnace hot zone. This is known as temperature lag. Hot zone temperature is controlled and measured through two (or more) thermocouples located close to the heating elements. One thermocouple, the control thermocouple, is connected to the thermal process controller which transmits signals to control the amount of power directed to the furnace elements.

    READ MORE: https://vacaero.com/information-resources/vac-aero-training/694-temperature-measurement-in-vacuum-furnaces.html

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Asked: October 10, 2023In:
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What is back streaming and back migration in vacuum technology?

back migrationbackstreaming
  1. VacuumFurnaces.com Answers
    This answer was edited.

    Back streaming and back migration are two phenomena that can occur in vacuum technology. Back Streaming: Back streaming refers to the movement of gas molecules from the high-pressure side of a vacuum system to the low-pressure side. This can happen when there is a pressure difference between two regRead more

    Back streaming and back migration are two phenomena that can occur in vacuum technology.

    Back Streaming:

    Back streaming refers to the movement of gas molecules from the high-pressure side of a vacuum system to the low-pressure side. This can happen when there is a pressure difference between two regions of the system, causing gas molecules to flow in the opposite direction of the desired vacuum. Back streaming can occur through leaks, permeation through materials, or through the pumping system itself. It can lead to contamination of the vacuum environment and a decrease in the overall vacuum level.

    Back Migration:

    Back migration, also known as back diffusion, is the migration of gas molecules from the pump exhaust back into the vacuum chamber. This can happen when the pressure in the pump exhaust is higher than the pressure in the vacuum chamber. Back migration can occur due to the design of the pumping system, improper sealing, or inadequate pumping speed. It can result in the reintroduction of contaminants or unwanted gases into the vacuum chamber, affecting the quality of the vacuum.

    Both back streaming and back migration are undesirable in vacuum technology as they can compromise the integrity of the vacuum environment and affect the performance of the system. Proper design, sealing, and maintenance of the vacuum system are important to minimize these phenomena and maintain a high-quality vacuum.

    Source: Vacuum Technology and Vacuum Design Handbook” by Karl Jousten

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Asked: October 6, 2023In:
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What are the consequences of back streaming and back migration in vacuum technology?

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  1. VacuumFurnaces.com Answers
    This answer was edited.

    Back streaming and back migration in vacuum technology can have several consequences that can impact the performance and integrity of the vacuum system. Here are some of the consequences: 1. Contamination: Back streaming and back migration can introduce contaminants into the vacuum chamber. When gasRead more

    Back streaming and back migration in vacuum technology can have several consequences that can impact the performance and integrity of the vacuum system. Here are some of the consequences:

    1. Contamination: Back streaming and back migration can introduce contaminants into the vacuum chamber. When gas molecules flow in the opposite direction of the desired vacuum, they can carry particles, dust, or other contaminants from the high-pressure side or pump exhaust back into the vacuum chamber. This contamination can affect the quality and cleanliness of the vacuum environment, which is crucial in many applications such as semiconductor manufacturing or scientific research.

    2. Decreased Vacuum Level: Back streaming and back migration can lead to a decrease in the overall vacuum level. When gas molecules flow from the high-pressure side to the low-pressure side, they increase the pressure in the vacuum system. This increase in pressure can reduce the effectiveness of the vacuum pump and compromise the desired vacuum level. It may require additional pumping or maintenance to restore the desired vacuum conditions.

    3. Reduced Pumping Efficiency: Back streaming and back migration can reduce the efficiency of the vacuum pump. When gas molecules flow in the opposite direction of the pumping direction, they can interfere with the pumping process and reduce the pumping speed. This can result in longer pump-down times, decreased throughput, and overall reduced efficiency of the vacuum system.

    4. Unwanted Gas Introduction: Back migration can result in the reintroduction of unwanted gases into the vacuum chamber. If the pressure in the pump exhaust is higher than the pressure in the vacuum chamber, gases from the pump exhaust can migrate back into the vacuum chamber. These gases may be contaminants or unwanted gases that can affect the process or experiment being conducted in the vacuum environment.

    To mitigate the consequences of back streaming and back migration, proper design, sealing, and maintenance of the vacuum system are essential. This includes using appropriate materials, ensuring proper sealing of components, and selecting suitable pumping systems with adequate pumping speed and efficiency.

    Source: Vacuum Technology and Vacuum Design Handbook” by Karl Jousten.

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