We use blocks like this in our electron beam welders to set the beam power, shape and focus on older machines (newer machines use a CPU/DSP controlled system). A small 25x25x50mm block sits on an adjustable height stand which is set to the height of the weld joint. You dial in the settings, hit the block with the beam and using the optics, visually check the focus and alignment. Then you move to the weld joint and start welding. For big power jobs we break out "the brick" which is 75x50x155. Its so heavy you need two hands to hold it and sometimes two people to place and line it up in the vacuum chamber.
Tungsten is the only metal you can reliably use as our machines have beam powers up to 15kW which can precisely deliver an enormous amount of heat into a pencil point sized area. Even at the common 1-3kW ranges the tungsten instantly liquefies when the beam turns on. Ive seen 1/2 thick aluminum turn into a puddle while the tungsten just gets a dent in it. You'd think copper is a good second bet but nope. Its good at heat sinking but melts way quicker.
> Tungsten is the only metal you can reliably use as our machines have beam powers up to 15kW which can precisely deliver an enormous amount of heat into a pencil point sized area. Even at the common 1-3kW ranges the tungsten instantly liquefies when the beam turns on.
I'm sorry - is there an error here? As I understand the rest of your comment, you use Tungsten because it does not liquify?
No error. The tungsten liquefies locally to the section of the block where the beam strikes but the surrounding tungsten stays solid. It's a poor heat conductor so it doesn't form a wide liquid puddle. With copper or aluminum the heat spreads rapidly and the pool grows wide very quickly.
Tungsten is the only metal you can reliably use as our machines have beam powers up to 15kW which can precisely deliver an enormous amount of heat into a pencil point sized area. Even at the common 1-3kW ranges the tungsten instantly liquefies when the beam turns on. Ive seen 1/2 thick aluminum turn into a puddle while the tungsten just gets a dent in it. You'd think copper is a good second bet but nope. Its good at heat sinking but melts way quicker.