I'm working with Metric Units (Unit Scale: 1). Result may differ when using other sphere sizes and some tweaking will be needed but I'll explain them later on.
Also, Fire or Plasma is transparent so it will be less visible in bright/white areas, just like fire in real life.
We will need only three of them. Sphere as a Flow object, Domain, and Force field which gives us noise to the flame.
Start with empty scene and Shift+A > Mesh > UV Sphere. Keep everything as is.
With Sphere selected hit Space and type Quick Smoke. Select it.
Now we need a Force field. Shift+A > Force Field > Turbulence.
Select Smoke Domain in the scene or in the Outliner and go to Physics tab.
- Resolution. We will leave it now at default value, but for final bake set it to 64.
- Time. Crank this up to have faster moving flames.
- Temp Diff. It's important one. Set it to 0 so flames will not go in any direction.
- Vorticity. Higher = more noise, lower = smoother flames.
Smoke Flames tab
- Speed. I've set it to 1. It will be connected to Force field settings (strength).
- Smoke. Set it to 0. We don't need any smoke.
- Vorticity. Same as Vorticity in Smoke tab.
Smoke Adaptive Domain and Smoke High Resolution tab
- Check Smoke Adaptive Domain.
- In Smoke High Resolution set it to 2 Divisions.
- Lower Noise Method to 1. You can try and play with it. Low setting will give smooth flames and really high make them raving.
Sphere (Smoke Flow) settings:
Select our Sphere, you should see settings right away in the same place where Domain was.
- Change Flow type to Fire.
- Flow rate is really fun to play with setting. Low value gives us really gentle flames, and high values will create total destruction.
Force field settings:
Select Force field (or Field in Outliner) and go to Physics tab (same as other objects).
- Strength. Set it to 35 or lower if you want shorter flames.
Note: If you set it to low value, flame will be shorter but also slower. Consider changing in Domain settings Time scale and Flame speed.
- Noise. Max it out. You can keyframe Seed to have even more noise.
We will need materials for our flame - this will be Domain, and for Sphere, to simply hide it.
Domain or Flame/Plasma material
- Select Smoke Domain and go to Node Editor.
- Delete everything there besides Material Output.
- Add Attribute node. Shift+A > Input > Attribute and type in it flame.
- Add Color Ramp. Shift+A > Converter > Color Ramp. Add there couple of colors you want, place as you want but remember to set last one (right one) to Alpha 0 and set color to it as well.
- Add Emission Shader. Shift+A > Shader > Emission.
- Connect everything as in picture above.
Sphere or Flow material
Just add Transparent BSDF to it. Nothing more.
Now you can play or bake (under Domain > Smoke cache settings) scene. Remember to set for final render Resolution to 64, and to have dark background.
Save a lot. I mean it. A lot.
Setup is really flexible, so don't afraid to test other settings.
I didn't achieve good stutter or flicker effect. The only thing I've come up was adding Brightness/Contrast node between Attribute and Emission and keyframing Brightness value, but this is horribly slow process. Maybe F-curves will help but I'm not good in animation.