Solar Flares
Using a Very Low Frequency (VLF) Radio to Detect Solar Flares
Equipment
- A Very Low Frequency (VLF) aerial
- An Aerial Tuning Unit (ATU)
- A VLF receiver
- A computer
- Optionally, a LabJack
The surface of the Sun is a maelstrom of plasma with a temperature of 5770K, however above the surface, in the Sun's atmosphere, the temperatures soar to tens of millions of degrees, and the plasma is accelerated to speeds approaching those of light. This energetic plasma is occasionally ejected in the form of a Solar flare. When these flares are directed towards the Earth, they can be disruptive, damaging satellites and powerlines. Fortunately most are too weak to cause damage but do have an effect on the Earth's atmosphere.
The ionosphere is a layer of the atmosphere in which charged particles reside. When a solar flare is directed at The Earth, the D layer of the ionosphere is distorted by these excess particles. It has been long known that radio transmission distances can be extend by bouncing radio signals off the ionosphere, but solar flares can extend this even further. A radio receiver can be used to detect solar flares by tuning in to a radio transmitter operating at a very low frequency. When a solar flare hits the Earth's atmosphere, causing distortion of the ionosphere D layer, the signal is increased. The radio signal is amplified and this amplification can be detected and displayed on a computer monitor.
The set up is shown above. All components can be bought either in kit form or ready made from UKRAA (see side panel). The aerial is a quadrant frame of non-conductive material e.g. wood, with 125 turns of 24 or 26 swg copper wire.
The receiver is a very low frequency radio receiver designed to operate at kiloherts frequencies: the UKRAA receiver is optimised to operate at 23.4Khz which is the frequency of transmission of a VLF source based at Ramsloh, Germany. The received signal is analogue so I connect my output to a laboratory data acquisition system called a LabJack.
The output from the LabJack is USB so the data can be read by a PC and displayed in chart form. The software I use is called Radio Sky Pipe available from Radio Sky
The image below, taken from Astronomy Log shows a solar flare as it would be seen on computer charting software:
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