Final answer:
H+ ions are put in the thylakoid space during the light dependent reactions by pumping them from the stroma and through the splitting of water.
Step-by-step explanation:
During the light dependent reactions of photosynthesis, two things happen to put H+ ions in the thylakoid space. First, as the electron passes along proteins in the electron transport chain, energy from the electron is used to pump hydrogen ions from the stroma into the thylakoid space, creating a high concentration of H+ ions. Second, the splitting of water also adds protons to the thylakoid lumen, further increasing the concentration of H+ ions.