A spark of short duration between two carbon electrodes produces carbon vapor which immediately condenses and forms carbon particles of about 30 nm size. The spark is obtained by discharging a capacitor triggered by a small high-frequency spark by means of a Tesla transformer. Thus the initiation of the spark and the discharge are decoupled. Both the distance of the electrodes, the energy of the discharge and the frequency of the sparks can be varied independently. Furthermore it is possible to charge the capacitor to voltages of only approximate to100 V for the discharge. A very stable and continuous operation of the generator has been achieved for tens of hours, particles sizes between 10 and 100 nm can be produced. (C) 2003 Elsevier Ltd. All rights reserved.