Can I install Windows 10 Technical Preview on Separate disk?

I have a laptop PC with windows 7 in it. I need to install windows 10 preview on a separate disk so that I can try it out since my laptop has a very small SSD. I do not want to interfere with it so I need a way of installing and running Windows on this external disk. Is it possible? How can I go about it? are there any negative impacts?
