subroutine trwimp(wtp,dwtp)
c--apply impulse due to field from many waves
c-- impulse lasts for a phase length of dwtp (degrees)
c-----------------------------------------------------------------------
      save
c
      include 'param_sz.h'
      include 'constcom.h'
      include 'coordcom.h'
      include 'misccom.h'
      include 'pcordcom.h'
      include 'syscom.h'
      include 'tstepcom.h'
      include 'wavescom.h'
      include 'ucom.h'
c
c--------------------------------------------------------------------------
c*
      ne=rne
      dwtmax=el(7,ne)
      if(dwtp.gt.dwtmax) dwtp=dwtmax
      zz=z
      rr=sqrt(x*x+y*y)
      call trwave(zz,rr,wez,wer,wbphi,iz,wtp)
      dummy=0.
      if(wez.eq.0..and.wer.eq.0.)return
      if((ip.eq.999).and.(nupar.eq.1))write(nimp,*) zz,dummy,dummy,wez
      if(rr.le.0.)rr=1.e-10
      eomdt=1.e-2/erest*dcon*dwtp
      dbgz=wez*eomdt
cliu  ezdbgz2=dbgz/dwtp		
      dgbr=eomdt*(wer-bgz/gamma*wbphi)
      bgz=bgz+dbgz
      bgx=bgx+dgbr*x/rr
      bgy=bgy+dgbr*y/rr
      gamma=sqrt(1.+bgx*bgx+bgy*bgy+bgz*bgz)
      return
      end
c++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*