Is the court abused its discretion in refusing to protect a witness in a sexual assault case from the possibility that the prosecution witnesses in the case colluded to corroborate their testimony?

Appellant argues the court abused its discretion in refusing to protect him from the possibility of the prosecution's witnesses talking to each other to bolster their stories and/or memories, or coordinate their testimony and thus shore up the weaknesses in their testimony. However, abuse of discretion is not presumed from a silent record, but must be clearly shown by [defendant]. (People v. Preyer (1985) 164 Cal.App.3d 568, 574; see People v. Stowell (2003) 31 Cal.4th 1107, 1114.)