Process for producing particles, comprising the following steps: - introducing, into a reaction chamber, at least one reaction stream (1, 100, 101, 102, 103, 104, 105, 106) comprising silicon as a first chemical element and propagating in a direction of flow, - projecting a radiation beam through the reaction chamber intersecting with each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) in one interaction zone per reaction stream, in order to form, in each reaction stream, particle cores comprising the first chemical element, and - introducing, into the reaction chamber, a second chemical element interacting with each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) in order to cover the particle cores with a layer comprising the second chemical element, this second chemical element being aluminium the second chemical element being introduced into the chamber in a gas stream (2; 7) surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106), characterized in that: - the second chemical element is introduced into the chamber in a peripheral gas stream surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106), emitted from several points distributed along a closed curve surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) and propagating in the direction of each reaction stream, the second chemical element being introduced into the chamber in the peripheral gas stream after the interaction zone of each reaction stream, and/or - it further comprises a step of introducing, into the reaction chamber, before the interaction zone of each reaction stream, a confining gas stream surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) and propagating in the direction of flow, the second chemical element being introduced into the chamber in the confining gas stream before the interaction zone of each reaction stream. - introducing, into a reaction chamber, at least one reaction stream (1, 100, 101, 102, 103, 104, 105, 106) comprising silicon as a first chemical element and propagating in a direction of flow, - projecting a radiation beam through the reaction chamber intersecting with each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) in one interaction zone per reaction stream, in order to form, in each reaction stream, particle cores comprising the first chemical element, and - introducing, into the reaction chamber, a second chemical element interacting with each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) in order to cover the particle cores with a layer comprising the second chemical element, this second chemical element being aluminium - the second chemical element is introduced into the chamber in a peripheral gas stream surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106), emitted from several points distributed along a closed curve surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) and propagating in the direction of each reaction stream, the second chemical element being introduced into the chamber in the peripheral gas stream after the interaction zone of each reaction stream, and/or - it further comprises a step of introducing, into the reaction chamber, before the interaction zone of each reaction stream, a confining gas stream surrounding each reaction stream (1, 100, 101, 102, 103, 104, 105, 106) and propagating in the direction of flow, the second chemical element being introduced into the chamber in the confining gas stream before the interaction zone of each reaction stream.