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**
**  RF HEATING AND CURRENT DRIVE INPUT FOR VLF MODULE
**  namelist rfsetup
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**
**  
**  vlfmod="enabled", then use multi-flux surface, multi-
**    harmonic, cyclotron  model for rf quaslinear diffusion,
**    Diffusion coefficient is according to Stix book (1993).
**    Region of wave interaction on each flux surface, 
**    polarizations, wavenumbers, harmonics, and frequencies
**    are  specified for up to nmodsa modes or harmonics (but
**    not both simultaneously).  The code calculates the
**    resulting bounce-averaged coefficients at each surface.
**    Can do eqmod="enabled"-cases, or eqmod="disabled" with
**    psimodel="spline" (but not presently "axitorus").
**    ONLY RELIABLE for electron cyclotron cases with
**    taunew="disabled".  (See taunew description, BobH, 010320).
**    
**  nrf, nonrf, and noffrf are used as above (or can use
**    vlhplse, vlhpon, vlhpoff, as above).
**
**  vlfmodes = number of wave-types of quasilinear excitation. (default=1.)
**
**  vlfbes = "enabled", use full Bessel functions in QL coeff.
**    (only possiblity at moment.)
**
**  vlfnpvar= "1/R" gives 1/R variation to parallel refractive index vlfnp,
**            "constant" gives constant vlfnp as function of position.
**
**  Each of following vlf-namelist variables is dimensioned 1:vlfmodes:
**
**  vlfharms()= number of harmonics.  (default=1.)
**
**  vlfdnorm()= Strength of QL diffusion coefficient, normalized
**    to collisional diffusion coefficient v_th(k)**2/tau_coll(e or i).
**    (See vlf.f).
**
**  vlffreq()= excitation frequency (Hz).
**
**  vlfharm1()= designates harmonic number of first of 
**    vlfnharms harmonics, or of each mode in the vlfmodes.gt.1
*     case (default=0.)
**
**  vlfnp()= central parallel refractive index at minimum B on the flux
**    surface, of a spectrum defined with vlfdnp and vlfddnp, below.
**    (Presently must be .lt.1. for relativistic case, 
**    for other than 0'th harmonics, 
**    i.e., no relativistic anomolous doppler cases (hyperbolic
**    resonance) at this time.  (default=0.5)
**
**  vlfdnp()= full width of par. ref. index, at full power. (default=.2)
**
**  vlfddnp()= additional region of par. ref. index, in which the
**    QL coeff. tapers to 0, like 0.5*cos((npar-0.5*(vlfnp+vlfdnp))*pi/vlfdnnp)
**    (default=.1)
**
**  vlfnperp()= perpendicular refractive index.
**
**  vlfeplus()= complex E_plus/abs(E) polarization. (default=0.,0.)
**
**  vlfemin() = complex E_minus/abs(E) polarizaion. (default=0.,0.)
**    (The parallel rf polarization is 
**    sqrt(1.-cabs(vlfeplus**2)-cabs(vlfemin**2))
**
**  vlfpol() = center of poloidal region on flux surface with
**    non-zero QL coeff. (degrees). (default=0.)
**
**  vlfdpol() = full width of poloidal region with full QL coeff.
**    (360. gives full flux surface). (default=360.)
**
**  vlfddpol()= taper distance of poloidal QL coeff, analagous to
**    vlfddnp above (degrees). (default=20.)
**
**  vlfparmn()=An additional window is put on the quasilinear
**    diffusion coefficient, for testing which velocity region
**    of the diffusion coefficient causes what current.  This
**    is the minimum parallel momemtum, units of vnorm.
**    default=-1.e100
**  vlfparmx()=Max parallel momentum. default=+1.e100
**  vlfpermn()=Min perpendicular momentum. default=0.
**  vlfpermx()=Max perpendicular momentum. default=+1.e100.
**   
**   
**
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