Increaing a field size for a record

Thomas Kennll has asked for the wisdom of the Perl Monks concerning the following question:

I wanted to increase all records field size in a file..

for eg) if i have a file like rij1

bash-2.03$ cat rij1
DSE 1232123456                            ABCDEF96DS0                 
+                              20100722      20120827KJHLK LKEDX      
+                                                                   05
+8305574               IAC 8                        S73               
+                                                                     
+         WERTYU
bash-2.03$
[download]

Currently the 2nd field has 11 characters, ie 1232123456

I want to increase the character size to 50, ie append the remaining with spaces.. result "1232123456(39 spaces) --> Total count should be 50 for this field " can someone help here..

Update: Thank You all for your help!! :)

I have a problem as the field are not necessarily field seperated.. If I could insert 39 spaces from postion 15 or from 15th character on all records will do.. Can anyone help.. Thanks again!!

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