From cac79bec2c0ae3f2a2fb3278591806007e9653ff Mon Sep 17 00:00:00 2001
From: RevathiJambunathan <revanathan@gmail.com>
Date: Mon, 2 Oct 2023 16:15:36 -0700
Subject: [PATCH] add RR

---
 Source/Particles/PulsarParameters.H                    |  2 ++
 Source/Particles/PulsarParameters.cpp                  |  4 ++++
 .../Pusher/UpdateMomentumBorisWithRadiationReaction.H  | 10 ++++++++++
 3 files changed, 16 insertions(+)

diff --git a/Source/Particles/PulsarParameters.H b/Source/Particles/PulsarParameters.H
index a208541f787..85c77a0c296 100644
--- a/Source/Particles/PulsarParameters.H
+++ b/Source/Particles/PulsarParameters.H
@@ -702,6 +702,8 @@ public:
     static amrex::Real m_depositbuffer_min;
     static amrex::Real m_depositbuffer_max;
     static int m_pml_cubic_sigma;
+    static amrex::Real m_gammarad_real;
+    static amrex::Real m_gammarad_scaled;
 private:
 };
 
diff --git a/Source/Particles/PulsarParameters.cpp b/Source/Particles/PulsarParameters.cpp
index 5fb57517eb4..48aa76ee0e8 100644
--- a/Source/Particles/PulsarParameters.cpp
+++ b/Source/Particles/PulsarParameters.cpp
@@ -143,6 +143,8 @@ amrex::Real Pulsar::m_gatherbuffer_max = 0.;
 amrex::Real Pulsar::m_depositbuffer_min = 0.;
 amrex::Real Pulsar::m_depositbuffer_max = 0.;
 int Pulsar::m_pml_cubic_sigma;
+amrex::Real Pulsar::m_gammarad_real = 1.;
+amrex::Real Pulsar::m_gammarad_scaled = 1.;
 
 Pulsar::Pulsar ()
 {
@@ -374,6 +376,8 @@ Pulsar::ReadParameters () {
     pp.query("depositbuffer_min",m_depositbuffer_min);
     pp.query("depositbuffer_max",m_depositbuffer_max);
     pp.get("pml_cubic_sigma", m_pml_cubic_sigma);
+    pp.query("gammarad_real", m_gammarad_real);
+    pp.query("gammarad_scaled", m_gammarad_scaled);
 }
 
 
diff --git a/Source/Particles/Pusher/UpdateMomentumBorisWithRadiationReaction.H b/Source/Particles/Pusher/UpdateMomentumBorisWithRadiationReaction.H
index b637f865ae8..4d7aea45445 100644
--- a/Source/Particles/Pusher/UpdateMomentumBorisWithRadiationReaction.H
+++ b/Source/Particles/Pusher/UpdateMomentumBorisWithRadiationReaction.H
@@ -8,6 +8,9 @@
 #define WARPX_PARTICLES_PUSHER_UPDATEMOMENTUM_BORIS_WITHRR_H_
 
 #include "UpdateMomentumBoris.H"
+#ifdef PULSAR
+#include "Particles/PulsarParameters.H"
+#endif
 
 #include <AMReX_REAL.H>
 
@@ -68,7 +71,14 @@ void UpdateMomentumBorisWithRadiationReaction(
     //Calculation of auxiliary quantities
     const amrex::ParticleReal bdotE = (bx_n*Ex + by_n*Ey + bz_n*Ez);
     const amrex::ParticleReal bdotE2 = bdotE*bdotE;
+#ifdef PULSAR
+    // To account for radiation reaction in the scaled pulsar simulation
+    // we scale the ultra-relativistic term, gamma_n with gamma_real/gamma_scaled
+    const amrex::ParticleReal gamma_scale_fac = Pulsar::m_gammarad_real/Pulsar::m_gammarad_scaled;
+    const amrex::ParticleReal coeff = gamma_scale_fac*gamma_scale_fac*gamma_n*gamma_n*(fl_q2-bdotE2);
+#else
     const amrex::ParticleReal coeff = gamma_n*gamma_n*(fl_q2-bdotE2);
+#endif
 
     //Radiation reaction constant
     const amrex::ParticleReal q_over_mc = q/(m*PhysConst::c);