Lower bounds on the class number of algebraic function fields defined   over any finite field
  We give lower bounds on the number of effective divisors of degree $\leq g-1$ with respect to the number of places of certain degrees of an algebraic function field of genus $g$ defined over a finite field. We deduce lower bounds and asymptotics for the class number, depending mainly on the number of places of a certain degree. We give examples of towers of algebraic function fields having a large class number. 
St\'ephane Ballet and Robert Rolland
math.AG