Tips for reducing particle flicker

[JH12]

I've been doing some basic playing with particles by turning a grid into particles with some wind and curve forces.  I like the look where I set the pscale to very small and push the count into the millions.  But I find that particularly around the edges of the particle system it looks very flickery and noisy when rendered. 

I've been rendering in Mantra with fairly default settings, and usually 3*3 samples.  

I understand that my particles are probably only one pixel in size each and there is plenty of movement in my system, but wondering if there are any tips on making the particles look more cohesive as a whole rather than so noisy.  

Thanks for any advice