This paper describes a study of triple-zone junction termination extension (JTE) as an edge termination for 10 kV power devices on 4H-SiC. Blocking voltage is obtained from two-dimensional numerical simulations using the MEDICI(TM) program, and is defined as the voltage where the ionization integral equals 0.9998 using impact ionization coefficients of Konstantinov, et al. Simulations are performed for triple-zone JTE on a 100 pm thick n-type epilayers doped 8X10(14) cm(-3). Each JTE zone is 100 mum wide. Blocking voltage is determined as a function of JTE dose for various values of the doping ratio cc, defined as the ratio of the dose of ring (i) to the dose of ring (i+1), where i = 1 for the inner ring, 2 for the next ring, and so on. Best results are obtained for constant alpha (i.e. alpha(1) = alpha(2) = alpha). For this epilayer, the optimum alpha is 1.3, i.e. this alpha maintains a blocking voltage greater than 10 kV over the widest range of JTE doses. The depth of the JTE has little effect on blocking voltage for depths less than 2 mum.