I'm an undergraduate intern at a government lab specializing in plasma energy and fusion research. I've been assigned an interesting technical project that involves gathering spectrometer data (line emissions, specifically) from an on-site plasma generator. It's basically a large tube with a Helmholtz coil surrounding it. Under certain conditions (magnetic, voltage, pressure, and electrode distance), plasma can be formed. See image below for reference.
We have a spectrometer here that has a fiber optic probe which intakes the light from a source, and shows the data on a computer software program. The issue I'm running into is that the plasma from the experiment isn't very intense, so the probe isn't picking up on it too much at all. I wanted to know if there are any optics "techniques" or concepts I could use to get a stronger reading. I was thinking of having a series of reflective surfaces nearby that can focus the light into the fixed probe. I've got some other ideas to test out, but came here for a bit of inspiration. Any advice would be greatly appreciated!
EDIT: After Floris' detailed answer, I'm going to take that advice and make a similar set up involving a lens. My initial set up involved an acrylic mirror slightly bent to converge the light at a point on the fiber optic cable. (See the picture below)
After contacting the company who made the spectrometer which I'm using, they suggested that since the incoming light is greatly divergent (as opposed to coming from one single source, like a ray, which.. the picture below depicts), that I should just order another fiber optic cable with a larger core aperture diameter. As it stands now, mine is 10um- he suggested to buy one that is around 200-400um. He stated that the set up I had wouldn't produce a significant result.
My mentor gave me the O.K. to just purchase the equipment. If you guys want to test out the experiment, it can be remotely accessed from any browser in the world. Google "RGDX IPPEX" and follow the instructions! Thank you again, Floris!
Another edit: Just wanted to cite the site that I used to get that image https://ricktu288.github.io/ray-optics/simulator/
For optics simulations, fantastic website!