diff --git a/process/current_drive.py b/process/current_drive.py
index 3c7cb4f7fe..7540e79e09 100644
--- a/process/current_drive.py
+++ b/process/current_drive.py
@@ -1479,6 +1479,27 @@ def cudriv(self) -> None:
                 / physics_variables.plasma_current
             )
 
+            # Calculate the dimensionless current drive efficiency for the primary heating method (ζ)
+            current_drive_variables.eta_cd_dimensionless_hcd_primary = self.calculate_dimensionless_current_drive_efficiency(
+                nd_plasma_electrons_vol_avg=physics_variables.nd_plasma_electrons_vol_avg,
+                rmajor=physics_variables.rmajor,
+                temp_plasma_electron_vol_avg_kev=physics_variables.temp_plasma_electron_vol_avg_kev,
+                c_hcd_driven=current_drive_variables.c_hcd_primary_driven,
+                p_hcd_injected=current_drive_variables.p_hcd_primary_injected_mw
+                * 1.0e6,
+            )
+
+            if current_drive_variables.p_hcd_secondary_injected_mw > 0.0:
+                # Calculate the dimensionless current drive efficiency for the secondary heating method (ζ)
+                current_drive_variables.eta_cd_dimensionless_hcd_secondary = self.calculate_dimensionless_current_drive_efficiency(
+                    nd_plasma_electrons_vol_avg=physics_variables.nd_plasma_electrons_vol_avg,
+                    rmajor=physics_variables.rmajor,
+                    temp_plasma_electron_vol_avg_kev=physics_variables.temp_plasma_electron_vol_avg_kev,
+                    c_hcd_driven=current_drive_variables.c_hcd_secondary_driven,
+                    p_hcd_injected=current_drive_variables.p_hcd_secondary_injected_mw
+                    * 1.0e6,
+                )
+
             # ===========================================================
 
             # Calculate the wall plug power for the secondary heating method
@@ -1911,6 +1932,52 @@ def cudriv(self) -> None:
                 )
             )
 
+    def calculate_dimensionless_current_drive_efficiency(
+        self,
+        nd_plasma_electrons_vol_avg: float,
+        rmajor: float,
+        temp_plasma_electron_vol_avg_kev: float,
+        c_hcd_driven: float,
+        p_hcd_injected: float,
+    ) -> float:
+        """
+                Calculate the dimensionless current drive efficiency, ζ.
+
+                This function computes the dimensionless current drive efficiency
+                based on the average electron density, major radius, and electron temperature.
+
+                :param nd_plasma_electrons_vol_avg: Volume averaged electron density in m^-3.
+                :type nd_plasma_electrons_vol_avg: float
+                :param rmajor: Major radius of the plasma in meters.
+                :type rmajor: float
+                :param temp_plasma_electron_vol_avg_kev: Volume averaged electron temperature in keV.
+                :type temp_plasma_electron_vol_avg_kev: float
+                :param c_hcd_driven: Current driven by the heating and current drive system.
+                :type c_hcd_driven: float
+                :param p_hcd_injected: Power injected by the heating and current drive system.
+                :type p_hcd_injected: float
+                :return: The calculated dimensionless current drive efficiency.
+                :rtype: float
+
+                :references:
+                    - E. Poli et al., “Electron-cyclotron-current-drive efficiency in DEMO plasmas,”
+                    Nuclear Fusion, vol. 53, no. 1, pp. 013011-013011, Dec. 2012,
+                    doi: https://doi.org/10.1088/0029-5515/53/1/013011.
+        ‌
+                    - T. C. Luce et al., “Generation of Localized Noninductive Current by Electron Cyclotron Waves on the DIII-D Tokamak,”
+                    Physical Review Letters, vol. 83, no. 22, pp. 4550-4553, Nov. 1999,
+                    doi: https://doi.org/10.1103/physrevlett.83.4550.
+        """
+
+        return (
+            (constants.ELECTRON_CHARGE**3 / constants.EPSILON0**2)
+            * (
+                (nd_plasma_electrons_vol_avg * rmajor)
+                / (temp_plasma_electron_vol_avg_kev * constants.KILOELECTRON_VOLT)
+            )
+            * (c_hcd_driven / p_hcd_injected)
+        )
+
     def output_current_drive(self):
         """
         Output the current drive information to the output file.
@@ -1990,6 +2057,13 @@ def output_current_drive(self):
             current_drive_variables.eta_cd_norm_hcd_primary,
             "OP ",
         )
+        po.ovarre(
+            self.outfile,
+            "Dimensionless current drive efficiency of primary system, ζ",
+            "(eta_cd_dimensionless_hcd_primary)",
+            current_drive_variables.eta_cd_dimensionless_hcd_primary,
+            "OP ",
+        )
         if current_drive_variables.i_hcd_primary == 10:
             po.ovarre(
                 self.outfile,
@@ -2211,6 +2285,13 @@ def output_current_drive(self):
             current_drive_variables.eta_cd_norm_hcd_secondary,
             "OP ",
         )
+        po.ovarre(
+            self.outfile,
+            "Dimensionless current drive efficiency of secondary system, ζ",
+            "(eta_cd_dimensionless_hcd_secondary)",
+            current_drive_variables.eta_cd_dimensionless_hcd_secondary,
+            "OP ",
+        )
         if current_drive_variables.i_hcd_secondary == 10:
             po.ovarre(
                 self.outfile,
diff --git a/process/data_structure/current_drive_variables.py b/process/data_structure/current_drive_variables.py
index 8c6fc0b70a..e7c3718978 100644
--- a/process/data_structure/current_drive_variables.py
+++ b/process/data_structure/current_drive_variables.py
@@ -216,10 +216,16 @@
 eta_cd_norm_hcd_primary: float = None
 """Normalised current drive efficiency for primary HCD system [(1.0e20 A)/(W m^2)]"""
 
+eta_cd_dimensionless_hcd_primary: float = None
+"""Dimensionless current drive efficiency for primary HCD system (ζ)"""
+
 
 eta_cd_norm_hcd_secondary: float = None
 """Normalised current drive efficiency for secondary HCD system [(1.0e20 A)/(W m^2)]"""
 
+eta_cd_dimensionless_hcd_secondary: float = None
+"""Dimensionless current drive efficiency for secondary HCD system (ζ)"""
+
 
 eta_cd_norm_ecrh: float = None
 """User input ECRH gamma (1.0e20 A/(W m^2))"""
@@ -424,7 +430,9 @@ def init_current_drive_variables():
     global f_radius_beam_tangency_rmajor
     global f_beam_tritium
     global eta_cd_norm_hcd_primary
+    global eta_cd_dimensionless_hcd_primary
     global eta_cd_norm_hcd_secondary
+    global eta_cd_dimensionless_hcd_secondary
     global eta_cd_norm_ecrh
     global xi_ebw
     global i_hcd_primary
@@ -497,6 +505,7 @@ def init_current_drive_variables():
     f_radius_beam_tangency_rmajor = 1.05
     f_beam_tritium = 1e-6
     eta_cd_norm_hcd_primary = 0.0
+    eta_cd_dimensionless_hcd_primary = 0.0
     eta_cd_norm_ecrh = 0.35
     xi_ebw = 0.8
     i_hcd_primary = 5
@@ -521,6 +530,7 @@ def init_current_drive_variables():
     n_beam_decay_lengths_core = 0.0
     n_beam_decay_lengths_core_required = 3.0
     eta_cd_norm_hcd_secondary = 0.0
+    eta_cd_dimensionless_hcd_secondary = 0.0
     eta_cd_hcd_secondary = 0.0
     p_ebw_injected_mw = 0.0
     p_hcd_ecrh_electric_mw = 0.0
diff --git a/process/io/plot_proc.py b/process/io/plot_proc.py
index 1e0d2c7258..eb2f4a3036 100644
--- a/process/io/plot_proc.py
+++ b/process/io/plot_proc.py
@@ -2587,13 +2587,13 @@ def plot_main_plasma_information(
         f"$\\mathbf{{Primary \\ system: {primary_heating}}}$ \n"
         f"Current driving power {mfile_data.data['p_hcd_primary_injected_mw'].get_scan(scan):.4f} MW\n"
         f"Extra heat power: {mfile_data.data['p_hcd_primary_extra_heat_mw'].get_scan(scan):.4f} MW\n"
-        f"$\\gamma_{{\\text{{CD,prim}}}}$: {mfile_data.data['eta_cd_hcd_primary'].get_scan(scan):.4f} A/W\n"
+        f"$\\gamma_{{\\text{{CD,prim}}}}$: {mfile_data.data['eta_cd_hcd_primary'].get_scan(scan):.4f} A/W  |   $\\langle\\zeta_{{\\text{{CD,prim}}}}\\rangle$: {mfile_data.data['eta_cd_dimensionless_hcd_primary'].get_scan(scan):.4f}  \n"
         f"$\\eta_{{\\text{{CD,prim}}}}$: {mfile_data.data['eta_cd_norm_hcd_primary'].get_scan(scan):.4f} $\\times 10^{{20}}  \\mathrm{{A}} / \\mathrm{{Wm}}^2$\n"
         f"Current driven by primary: {mfile_data.data['c_hcd_primary_driven'].get_scan(scan) / 1e6:.3f} MA\n\n"
         f"$\\mathbf{{Secondary \\ system: {secondary_heating}}}$ \n"
         f"Current driving power {mfile_data.data['p_hcd_secondary_injected_mw'].get_scan(scan):.4f} MW\n"
         f"Extra heat power: {mfile_data.data['p_hcd_secondary_extra_heat_mw'].get_scan(scan):.4f} MW\n"
-        f"$\\gamma_{{\\text{{CD,sec}}}}$: {mfile_data.data['eta_cd_hcd_secondary'].get_scan(scan):.4f} A/W\n"
+        f"$\\gamma_{{\\text{{CD,sec}}}}$: {mfile_data.data['eta_cd_hcd_secondary'].get_scan(scan):.4f} A/W  |   $\\langle\\zeta_{{\\text{{CD,sec}}}}\\rangle$: {mfile_data.data['eta_cd_dimensionless_hcd_secondary'].get_scan(scan):.4f}  \n"
         f"$\\eta_{{\\text{{CD,sec}}}}$: {mfile_data.data['eta_cd_norm_hcd_secondary'].get_scan(scan):.4f} $\\times 10^{{20}}  \\mathrm{{A}} / \\mathrm{{Wm}}^2$\n"
         f"Current driven by secondary: {mfile_data.data['c_hcd_secondary_driven'].get_scan(scan) / 1e6:.3f} MA\n"
     )
diff --git a/tests/unit/test_current_drive.py b/tests/unit/test_current_drive.py
index f18e27ed82..762f52276f 100644
--- a/tests/unit/test_current_drive.py
+++ b/tests/unit/test_current_drive.py
@@ -322,3 +322,43 @@ def test_cudriv_primary_electron_bernstein(current_drive):
     assert current_drive_variables.p_hcd_injected_total_mw == pytest.approx(
         257.72205307406523, rel=1e-6
     )
+
+
+@pytest.mark.parametrize(
+    "nd_plasma_electrons_vol_avg, rmajor, temp_plasma_electron_vol_avg_kev, c_hcd_driven, p_hcd_injected",
+    [
+        (1e20, 1.0, 1.0, 1.0, 1.0),
+    ],
+)
+def test_calculate_dimensionless_current_drive_efficiency_simple(
+    nd_plasma_electrons_vol_avg,
+    rmajor,
+    temp_plasma_electron_vol_avg_kev,
+    c_hcd_driven,
+    p_hcd_injected,
+):
+    plasma_profile = PlasmaProfile()
+    cd = CurrentDrive(
+        plasma_profile=plasma_profile,
+        electron_cyclotron=ElectronCyclotron(plasma_profile),
+        ion_cyclotron=IonCyclotron(plasma_profile),
+        lower_hybrid=LowerHybrid(plasma_profile),
+        neutral_beam=NeutralBeam(plasma_profile),
+        electron_bernstein=ElectronBernstein(plasma_profile),
+    )
+    expected = (
+        (constants.ELECTRON_CHARGE**3 / constants.EPSILON0**2)
+        * (
+            (nd_plasma_electrons_vol_avg * rmajor)
+            / (temp_plasma_electron_vol_avg_kev * constants.KILOELECTRON_VOLT)
+        )
+        * (c_hcd_driven / p_hcd_injected)
+    )
+    result = cd.calculate_dimensionless_current_drive_efficiency(
+        nd_plasma_electrons_vol_avg,
+        rmajor,
+        temp_plasma_electron_vol_avg_kev,
+        c_hcd_driven,
+        p_hcd_injected,
+    )
+    assert result == pytest.approx(expected, rel=1e-12)