Campbell has agreed to join the Spanish side on a season-long loan.
The 20-year-old joined Arsenal from Costa Rican side Deportivo Saprissa in August 2011.
Campbell spent last season on loan at French side FC Lorient.
Campbell has agreed to join the Spanish side on a season-long loan.
The 20-year-old joined Arsenal from Costa Rican side Deportivo Saprissa in August 2011.
Campbell spent last season on loan at French side FC Lorient.
