Heat pipe with axial wick

1. A heat pipe, comprising:

an evaporator portion;

a condenser portion; and

at least one flexible portion sealingly coupled between the evaporator portion and the condenser portion, the at least one flexible portion comprising:

a flexible tube comprising an interior volume and a plurality of inner edges; and

a flexible separator plate comprising two lateral edges that are disposed proximate to the inner edges of the tube,

wherein the interior volume comprises a gas-phase passage on a first side of the flexible separator plate and a liquid-phase artery on an opposing second side of the flexible separator plate, the separator plate further comprising a first plane that passes through the two lateral edges when the separator plate is flat,

wherein the separator plate and flexible tube are configured such that the at least one flexible portion is flexible in at least a second plane that is perpendicular to the first plane,

wherein the first plane comprises a centerline that is midway between the two lateral edges when the separator plate is flat,

wherein the flexible portion is flexible in any plane that passes through the centerline of the separator plate,

wherein the evaporator portion comprises a separation plate, a gas-phase passage, a liquid-phase artery, and a vent hole formed through the separator plate so as to connect the gas-phase passage to the liquid-phase artery, the vent hole comprising a diameter that is greater than or equal to a diameter of the largest circle that can be inscribed within the liquid-phase artery in a cross-section of the evaporator portion taken perpendicular to a centerline of the evaporator portion,

wherein the flexible tube comprises a bellows tube that comprises a plurality of individual bellows each comprising an opening defined by the lateral edge of the separation plate and an inner surface of the individual bellows, and

wherein each opening has a respective hydraulic diameter that is less than the diameter of the vent hole.

2. The heat pipe of claim 1 , wherein:

the first plane comprises a centerline that is midway between the two lateral edges when the separator plate is flat; and

the flexible portion is flexible in any plane that passes through the centerline of the separator plate.

3. The heat pipe of claim 1 , further comprising a coil spring disposed in the gas-phase passage of the flexible portion.

4. The heat pipe of claim 3 , wherein:

the coil spring comprises a plurality of coils;

at least one of the plurality of coils is in contact with at least one of the inner edges of the flexible tube; and

at least one of the plurality of coils is in contact with the separation plate.