CRYO PUMP – AN ESSENTIAL PART OF THE HIGHEST QUALITY EQUIPMENTS

I. WHAT IS CRYO PUMP?

-Cryo Pump is an air conditioner or “cold air conditioner” that is a machine that vacuums gas and vapor by condensing them on a cold surface, but is only effective for certain types of gas. The effectiveness depends on the freezing point and boiling point of the device to regulate the cold temperature. Sometimes Pour Cryo is used to prevent other contamination contaminants, such as in front of spray diffusers to beat back oil, or in front of probes to keep out water. -Cryotrap could also offer another breath application, where molecules would increase their residence time on a cold surface without actually freezing (supercooling). There is a level of analysis at the surface and is bounced off of it. Functions will be lost when slow molecules are rerun. For example, hydrogen gas does not condense at 8K but it can get cold. This effectively collects molecules over a long period of time and removes them from a cold, vacuum-like environment. -Cryo pump can create clean vacuum of 10^-7Pa or less. In addition, the Cryo quantity is also fast gas removal in a widely applicable range from 10^-1Pa to 10^-7Pa.

II. ULVAC’S CRYO PUMP

U4H U6H U8H, U8HL, U8HSP, U8H-U U10H, U10HSP U12H, U12HSP, U12HL U16, U16P U20P, U20H U22H, U22P, U22WB U30H

III. CRYO PUMP STRUCTURE

IV. CRYO PUMP SYSTEM

Cryo pump – Compressor – Hose

V. OPERATION PRINCIPLES OF CRYO PUMP

1. Cryo Pump are usually cooled by Helium gas compressed through a compressor

Baffles are often attached to the cold head to expand the surface area available for condensation, but they also increase the absorption of radiant heat by the Cryo pump. Over time, the surface is eventually saturated with condensed water, ice formation occurs, so the pumping speed gradually drops to zero. The Cryo pump will still keep the gas trapped as long as it remains cold but it will not condense new gas from the leak or backflow until it is regenerated. The freezing process occurs very quickly in low vacuum environments, so Cryo pumps are only used in high or ultra-high vacuum systems. -The Cryo pump operates on the principle that gas can be condensed and held at extremely low vapor pressure, achieving high speed and throughput. The cold head consists of a cylinder with two stages and a moving transducer assembly. Together these create closed-loop refrigeration at temperatures ranging from 60K to 80K for the first stage refrigeration unit and from 10K to 20K for the second stage refrigeration unit.

2. A Cryo pump has multiple stages at different low temperatures

ith the outer stages shielding the coldest inner stages. The outer stages condense high boiling point gases such as water and oil, thereby saving the surface area and cooling capacity of the inner stages for lower boiling point gases such as Nitrogen. -Cryo pumps do not run continuously in machines such as diffusion pumps or Turbo molecular pumps. Gases are absorbed and condensed in the 15K cold baffles, so it needs to be degassed and regenerated regularly. During this regeneration process, the Cryo pump is heated up, and the condensed and absorbed gas is converted into gas. If a large amount of gas is pumped, there is a risk of explosion. To prevent the risk of explosion, all Cryo pumps have a pressure relief valve. The operating pressure of the pressure reducing valve has been set at 20kPa.

VI. COOLING PRINCIPLES

1. Principle of cooling Structure of Cryo pump refrigeration equipment

a)First, the displacer is placed at the bottom of the cylinder, the low pressure valve closes, the high pressure valve opens. Compressed helium gas is introduced into the cylinder b)Displacer is moved up. The pressure inside the cylinder increases. The cooling gas will fill the space below the piston. c) When the cylinder is at its highest position, the high pressure valve closes and the low pressure valve opens. The compressed helium passes through the regenerator into the lower part of the cylinder. While passing through the regenerator, the Helium gas is cooled as it expands d) The low temperature part reaches the lowest pressure. The Displacer is moved down and the expanding Helium gas is pumped by the compressor through the open low pressure valve. Finally the low pressure valve is closed and the cycle is repeated.

VII. APPLICATIONS

– Cryo pumps are widely used, with a wide range of applications for both industry and scientific research on Oled screens, lighting, semiconductors, electrical equipment, sensors or optical films such as evaporators. vacuum, sputtering machine, plating machine……..