There are several things to clear up here before I could answer this question.

• Show is typically used with Graphics expressions. I'm not sure that this would work even if the iterators resolved the way you expect.
• Your Function assigns a value to its argument. It might be simpler to just use Set directly, or maybe define some helper function so that this piece of the puzzle is clearer.
• The value that Function sets its argument to is a Manipulate, so it seems like what you're trying to do is create a bunch of Manipulate expressions. It might be easier to just create a single Manipulate that includes the additional parameters of Mass and Radius.
• You seem to be creating a symbol that will be the thing that gets assigned a value by the Function, but the symbol itself shows up inside the value you're assigning to it. I'm worried there'll be some sort of infinite recursion happening here.

Here is a possible line of thought. Before trying to "one-line" it, just break it up into pieces:

(*A function for creating a symbol*)
NameMassRadius[mass_, radius_] := 
  Symbol["CombinedCartesianPlot\[NumberSign]" <>ToString[mass] <> "\[NumberSign]" <> ToString[radius]]

(*A function for creating a value to be assigned to a variable*)
MassRadiusValue[mass_, radius_] := SomeFunction[mass, radius]

(*A function to do the assignment*)
AssignMassRadius[name_Symbol, mass_, radius_] := (name = MassRadiusValue[mass, radius])

(*Set up a tabular representation of the assignments you want*)
assignmentData = 
 Table[{NameMassRadius[mass, radius], MassRadiusValue[mass, radius]}, {mass, 1, 3}, {radius, 1, 3}]

(*Do the assignments*)
Scan[Apply[Set], assignmentData, {-3}]

Now, if that all fits in with what you're trying to do, then the next step would be figuring out what MassRadiusValue should really be, presumably some Manipulate expression.

Lance,

You should not be using strings to construct expressions in Mathematica except in unusual cases. In this case you can do what you want directly without any strings. I can't understand what you want the final output to look like unless you describe it or draw a picture, but a simple example of a something related would look like this:

Manipulate[
 Column[Table[
   Show[Plot[a * x^(2 + (b - 1)/10), {x, 0, 3.5}], 
    ListPlot[a*{1, 4, 9}], ImageSize -> Medium], {b, 4}]], {a, 1, 5}]

or a grid like this:

Manipulate[
 Grid[Partition[
   Table[
    Show[Plot[a * x^(2 + (b - 1)/10), {x, 0, 3.5}], 
     ListPlot[a*{1, 4, 9}], ImageSize -> Medium], {b, 4}], 2]], {a, 1,
   5}]

You use Table to create a list of Plots and partition it into a Grid (or use Table with two iterators). The you can use manipulate to alter Parameters that you want to change by hand.

Regards,

Neil