A high voltage inductive adder (100, 200, 300) comprising: a first circuit comprising: a first printed circuit board, the first printed circuit board having an inductance less than about 300 nH; a first source (105A, 205A) disposed on the first printed circuit board, the first source comprising an energy storage capacitor; a first switch (110A, 210A) disposed on the first printed circuit board and electrically coupled with the first source; a first transformer core (115A, 220A, 315) disposed on the first printed circuit board; and a first plurality of primary windings wound about the first transformer core and electrically coupled with the first switch; a second circuit comprising: a second printed circuit board stacked on top of the first printed circuit board, the second printed circuit board having an inductance less than about 300 nH; a second source (105B, 205B) disposed on the second printed circuit board; a second switch (110B, 210B) disposed on the second printed circuit board and electrically coupled with the second source; a second transformer core (115B, 220B, 315) disposed on the second printed circuit board; and a second plurality of primary windings wound about the second transformer core and electrically coupled with the second switch; a secondary winding wound around both the first transformer core and the second transformer core with a plurality of turns, wherein the turns are grouped in four or eight clusters distributed radially around the first transformer core and the second transformer core; and an output coupled with the secondary winding; wherein the stray inductance of the first circuit is less than about 30 nH as measured from the primary side of the circuit, and wherein the stray inductance of the second circuit is less than about 30 nH as measured from the primary side of the circuit. a first circuit comprising: a first printed circuit board, the first printed circuit board having an inductance less than about 300 nH; a first source (105A, 205A) disposed on the first printed circuit board, the first source comprising an energy storage capacitor; a first switch (110A, 210A) disposed on the first printed circuit board and electrically coupled with the first source; a first transformer core (115A, 220A, 315) disposed on the first printed circuit board; and a first plurality of primary windings wound about the first transformer core and electrically coupled with the first switch; a first printed circuit board, the first printed circuit board having an inductance less than about 300 nH; a first source (105A, 205A) disposed on the first printed circuit board, the first source comprising an energy storage capacitor; a first switch (110A, 210A) disposed on the first printed circuit board and electrically coupled with the first source; a first transformer core (115A, 220A, 315) disposed on the first printed circuit board; and a first plurality of primary windings wound about the first transformer core and electrically coupled with the first switch; a second circuit comprising: a second printed circuit board stacked on top of the first printed circuit board, the second printed circuit board having an inductance less than about 300 nH; a second source (105B, 205B) disposed on the second printed circuit board; a second switch (110B, 210B) disposed on the second printed circuit board and electrically coupled with the second source; a second transformer core (115B, 220B, 315) disposed on the second printed circuit board; and a second plurality of primary windings wound about the second transformer core and electrically coupled with the second switch; a second printed circuit board stacked on top of the first printed circuit board, the second printed circuit board having an inductance less than about 300 nH; a second source (105B, 205B) disposed on the second printed circuit board; a second switch (110B, 210B) disposed on the second printed circuit board and electrically coupled with the second source; a second transformer core (115B, 220B, 315) disposed on the second printed circuit board; and a second plurality of primary windings wound about the second transformer core and electrically coupled with the second switch; a secondary winding wound around both the first transformer core and the second transformer core with a plurality of turns, wherein the turns are grouped in four or eight clusters distributed radially around the first transformer core and the second transformer core; and an output coupled with the secondary winding; wherein the stray inductance of the first circuit is less than about 30 nH as measured from the primary side of the circuit, and wherein the stray inductance of the second circuit is less than about 30 nH as measured from the primary side of the circuit.