density of active particles on reel tapes?

[bandorr]

Hi I'll like to know what is density of active particles on reel-to-reel magnetic tapes per mm or cm.I need this for a project I'm involved.

Maybe i'm not asking the question in the right place(sorry for that if the case) also I realize that the exact number is probably closely guarded secret, but I'm REALLY interested in this matter.

Thanks in advance.

[Les]

Well, i'll respond since no one else has.

Particle density per unit length has no meaning unless you specify a track width, right?

If you are thinking of old-style open reel analog audio tape, typical mean particulate density was about 3x10^2 particles per micron ^3. (from one of my old engineering texts)

Coating thickness was typically 10 microns or so.

Given a track width you can calculate particles per unit length with these two numbers.

The values varied HUGELY for different media...i.e. reel to reel, cassette, video, etc as well as composition like ferric oxide, cromium dioxide, metal particle, etc.

Coercivity and noise were strong functions of particle size distribution.

Curious...why in the world do you want to know this?

[bandorr]

Thanks Les this is exactly what I looking for!

This is related to an audio engine project that i started about 2 years ago.