Question: Iterate with alphabets in maple

Hello,
I want to update Alphabets in my ‘for loop’ instead of numbers. Please look at the code below:

for Tl from 263 by 5 to 313 do
   for Ql from 25 by 25 to 300 do
        myvel:= my_porous(Ql, Tl, ratiol);
        Export(<myvel>, "HPporousmodel.xlsx", 1, my_alph[vcount]);
        vcount := vcount+1;

   end do

end do
 

Here, my_alph is a manually created alphabets corresponding to excel columns as below:

my_alph:=[ "A1", "B1", "C1", "D1", "E1", "F1", "G1", "H1", "I1", "J1", "K1", "L1", "M1", "N1", "O1", "P1", "Q1", "R1", "S1", "T1", "U1", "V1", "W1", "X1", "Y1", "Z1", "AA1", "AB1", "AC1", "AD1", "AE1", "AF1", "AG1", "AH1", "AI1", "AJ1", "AK1", "AL1", "AM1", "AN1", "AO1", "AP1", "AQ1", "AR1", "AS1", "AT1", "AU1", "AV1", "AW1", "AX1", "AY1", "AZ1", "BA1", "BB1", "BC1", "BD1", "BE1", "BF1", "BG1", "BH1", "BI1", "BJ1", "BK1", "BL1", "BM1", "BN1", "BO1", "BP1", "BQ1", "BR1", "BS1", "BT1", "BU1", "BV1", "BW1", "BX1", "BY1", "BZ1"]:

The idea is to export the velocity vector that I get from proc (my_porous(Ql, Tl, ratiol)) in to an excel sheet (HPporousmodel.xlsx)with the command (Export(<myvel>, "HPporousmodel.xlsx", 1, my_alph[vcount]);). I want to export the velocities into a new column for every iteration starting from A, B, C,….. and so on. However, since I don’t know how to do that I’ve used a manually created list my_alph. This has a big disadvantage of restricting the number of times I can loop. For this case, I can only loop (3*26=78 times). Anything more asks for manually increasing the entries of my my_alph list. I want to loop for 100's of times which is becoming a big problem with this method.

Can anyone please help me in automating this without any such constraints as we do with numbers (like we have done for vcount here)?
 

Thank you.