Olsen, V.K.B. Adli, E. Muggli, P. Vieira, J. Loading of Wakefields in a Plasma Accelerator Section Driven by a Self-Modulated Proton Beam JACoW Geneva, Switzerland 978-3-95450-180-9 10.18429/JACoW-NAPAC2016-TUA4CO03 English 457-459 TUA4CO03 ion plasma simulation proton wakefield Contribution to a conference proceedings 2017 2017-01 http://dx.doi.org/10.18429/JACoW-NAPAC2016-TUA4CO03 https://jacow.org/napac2016/papers/tua4co03.pdf Using parameters from the AWAKE project and particle-in-cell simulations we investigate beam loading of a plasma wake driven by a self-modulated proton beam. Addressing the case of injection of an electron witness bunch after the drive beam has already experienced self-modulation in a previous plasma, we optimise witness bunch parameters of size, charge and injection phase to maximise energy gain and minimise relative energy spread and emittance of the accelerated bunch.