MICROCHANNEL COOLING FOR A HIGH-ENERGY PARTICLE TRANSMISSION WINDOW, AN RF TRANSMISSION WINDOW, AND VLSI HEAT DISSIPATION

The transmission of energetic particles from vacuum to atmospheric pre ssure through a window results in some energy deposition within the wi ndow. This energy heats the window, increases its temperature, reduces its mechanical strength, and so limits the particle flux through the window. An analysis of heat transport indicates that a transmission wi ndow that incorporates microchannel cooling within the window can incr ease its heat dissipation, thereby increasing beam flux by several ord ers of magnitude. This increase occurs because the convective heat-tra nsfer coefficient can increase to similar to 1 MW/m(2) x K for fully d eveloped turbulence in 131 mu m diameter capillary tubing. Mechanical and thermal constraints are discussed, as well as the hydraulic system necessary to achieve appropriate fluid flow. Experimental heat dissip ation using 131 mu m capillary tubes in a seven-tube manifold implies that a 5 cm diameter foil window could dissipate 2.7 kW/cm(2) continuo usly. Design examples include a 30 mA/cm(2) electron-beam window, a 72 2 W/cm(2) RF window, and 950 W/cm(2) very large scale integration (VLS I) cooling.