A cryopump has a cryogenic refrigerator with cold and colder stages that cool a radiation shield, a primary cryopumping array and a frontal array. The frontal array is coupled to the cold stage and is spaced from and wrapped around the frontally facing envelope of the primary cryopumping array. The frontal array may be recessed from the frontal opening and closer to the primary cryopumping array than to the frontal opening.

Systems and methods that maintain a vacuum for a long period of time in a portable vacuum chamber are disclosed. Systems and methods for the maintenance of a vacuum in cryogenic Dewars for imaging systems with high gas loads using an integral pump and getter are also disclosed.

Ion separation media are described herein employing thermoelectric materials and architectures. In some embodiments, an ion separation medium comprises a layer of inorganic nanoparticles having a Seebeck coefficient sufficient to transport ionic species in a liquid medium along surfaces of the layer in the presence of a thermal gradient.

Ion separation media are described herein employing thermoelectric materials and architectures. In some embodiments, an ion separation medium comprises a layer of inorganic nanoparticles having a Seebeck coefficient sufficient to transport ionic species in a liquid medium along surfaces of the layer in the presence of a thermal gradient.

Provided herein are passive microfluidic pumps. The pumps can comprise a fluid inlet, an absorbent region, a resistive region fluidly connecting the fluid inlet and the absorbent region, and an evaporation barrier enclosing the resistive region, the absorbent region, or a combination thereof. The resistive region can comprise a first porous medium, and a fluidly non-conducting boundary defining a path for fluid flow through the first porous medium from the fluid inlet to the absorbent region. The absorbent region can comprise a fluidly non-conducting boundary defining a volume of a second porous medium sized to absorb a predetermined volume of fluid imbibed from the resistive region. The resistive region and the absorbent region can be configured to establish a capillary-driven fluid front advancing from the fluid inlet through the resistive region to the absorbent region when the fluid inlet is contacted with fluid.

Provided herein are passive microfluidic pumps. The pumps can comprise a fluid inlet, an absorbent region, a resistive region fluidly connecting the fluid inlet and the absorbent region, and an evaporation barrier enclosing the resistive region, the absorbent region, or a combination thereof. The resistive region can comprise a first porous medium, and a fluidly non-conducting boundary defining a path for fluid flow through the first porous medium from the fluid inlet to the absorbent region. The absorbent region can comprise a fluidly non-conducting boundary defining a volume of a second porous medium sized to absorb a predetermined volume of fluid imbibed from the resistive region. The resistive region and the absorbent region can be configured to establish a capillary-driven fluid front advancing from the fluid inlet through the resistive region to the absorbent region when the fluid inlet is contacted with fluid.

Provided herein are passive microfluidic pumps. The pumps can comprise a fluid inlet, an absorbent region, a resistive region fluidly connecting the fluid inlet and the absorbent region, and an evaporation barrier enclosing the resistive region, the absorbent region, or a combination thereof. The resistive region can comprise a first porous medium, and a fluidly non-conducting boundary defining a path for fluid flow through the first porous medium from the fluid inlet to the absorbent region. The absorbent region can comprise a fluidly non-conducting boundary defining a volume of a second porous medium sized to absorb a predetermined volume of fluid imbibed from the resistive region. The resistive region and the absorbent region can be configured to establish a capillary-driven fluid front advancing from the fluid inlet through the resistive region to the absorbent region when the fluid inlet is contacted with fluid.

Provided herein are passive microfluidic pumps. The pumps can comprise a fluid inlet, an absorbent region, a resistive region fluidly connecting the fluid inlet and the absorbent region, and an evaporation barrier enclosing the resistive region, the absorbent region, or a combination thereof. The resistive region can comprise a first porous medium, and a fluidly non-conducting boundary defining a path for fluid flow through the first porous medium from the fluid inlet to the absorbent region. The absorbent region can comprise a fluidly non-conducting boundary defining a volume of a second porous medium sized to absorb a predetermined volume of fluid imbibed from the resistive region. The resistive region and the absorbent region can be configured to establish a capillary-driven fluid front advancing from the fluid inlet through the resistive region to the absorbent region when the fluid inlet is contacted with fluid.

A cryopump includes a cryopanel, and an adsorption area provided on the cryopanel and capable of adsorbing a non-condensable gas, in which the adsorption area includes a non-combustible adsorbent containing silica gel as a main component thereof. The adsorption area includes a non-combustible adsorbent containing silica gel as a main component thereof.

A cryopump includes a cryopanel, and an adsorption area provided on the cryopanel and capable of adsorbing a non-condensable gas, in which the adsorption area includes a non-combustible adsorbent containing silica gel as a main component thereof. The adsorption area includes a non-combustible adsorbent containing silica gel as a main component thereof.