System for purifying argon by cryogenic distillation, comprising i. A single column surmounted by a top-end condenser, a fluid inlet in the lower part of the column, a fluid outlet in the upper part of the column, and N distillation sections where N≥4, each section being made up of a stack of units of structured packing, of the cross-corrugated type, each unit comprising a packet of rectangular corrugated sheets, of which at least the two uppermost sections (T1, T2) of the column are equipped respectively with a first liquid distributor (D 1) and with a second liquid distributor (D 2), the second distributor being capable of performing a function of mixing together liquids that fall onto the distributor, each of the first and second distributors being positioned above the respective section and of which at least two lowermost sections (TN-1, TN) of the column are respectively equipped with a (N-1)th and an Nth liquid distributor (D N-1, D N) capable of performing a function of mixing together liquids that fall onto the distributor, and which is arranged above the respective section, or ii. A first column and a second column surmounted by a top-end condenser, a fluid inlet in the lower part of the first column, a fluid outlet in the upper part of the second column, means connecting the top end of the first column and the bottom end of the second column to allow a bottom liquid from the second column to be conveyed to the top end of the first column and allow a top-end gas from the first column to be conveyed to the second column, the first and second columns comprising in total N distillation sections where N≥4, each section being made up of a stack of units of structured packing, of the cross-corrugated type, each unit comprising a packet of rectangular corrugated sheets, of which at least the two uppermost sections of the second column are equipped respectively with a first liquid distributor (D 1) and with a second liquid distributor (D 2) capable of performing a function of mixing together liquids that fall onto the distributor, each of the first and second distributors being positioned above the respective section and of which at least two lowermost sections of the first column are respectively equipped with a (N-1)th and an Nth liquid distributor (D N-1, D N) capable of performing a function of mixing together liquids that fall onto the distributor, and which is arranged above the respective section, characterized in that: □ the first, second, (N-1)th and Nth distributors are each dimensioned to contain a maximum height of liquid head, that (those) of the first and second distributors being greater than that (those) of the (N-1)th and Nth distributors. i. A single column surmounted by a top-end condenser, a fluid inlet in the lower part of the column, a fluid outlet in the upper part of the column, and N distillation sections where N≥4, each section being made up of a stack of units of structured packing, of the cross-corrugated type, each unit comprising a packet of rectangular corrugated sheets, of which at least the two uppermost sections (T1, T2) of the column are equipped respectively with a first liquid distributor (D 1) and with a second liquid distributor (D 2), the second distributor being capable of performing a function of mixing together liquids that fall onto the distributor, each of the first and second distributors being positioned above the respective section and of which at least two lowermost sections (TN-1, TN) of the column are respectively equipped with a (N-1)th and an Nth liquid distributor (D N-1, D N) capable of performing a function of mixing together liquids that fall onto the distributor, and which is arranged above the respective section, or ii. A first column and a second column surmounted by a top-end condenser, a fluid inlet in the lower part of the first column, a fluid outlet in the upper part of the second column, means connecting the top end of the first column and the bottom end of the second column to allow a bottom liquid from the second column to be conveyed to the top end of the first column and allow a top-end gas from the first column to be conveyed to the second column, the first and second columns comprising in total N distillation sections where N≥4, each section being made up of a stack of units of structured packing, of the cross-corrugated type, each unit comprising a packet of rectangular corrugated sheets, of which at least the two uppermost sections of the second column are equipped respectively with a first liquid distributor (D 1) and with a second liquid distributor (D 2) capable of performing a function of mixing together liquids that fall onto the distributor, each of the first and second distributors being positioned above the respective section and of which at least two lowermost sections of the first column are respectively equipped with a (N-1)th and an Nth liquid distributor (D N-1, D N) capable of performing a function of mixing together liquids that fall onto the distributor, and which is arranged above the respective section, □ the first, second, (N-1)th and Nth distributors are each dimensioned to contain a maximum height of liquid head, that (those) of the first and second distributors being greater than that (those) of the (N-1)th and Nth distributors.