Controller for Particle System Circle

ParticleSystemCircle.cs

using Sirenix.OdinInspector;
using UnityEngine;

public class ParticleSystemCircle : MonoBehaviour {
    
    private ParticleSystem _particleSystem;
    private ParticleSystem.MainModule _main;
    private ParticleSystem.ShapeModule _shape;
    private ParticleSystem.EmissionModule _emission;
    private ParticleSystem.VelocityOverLifetimeModule _velocity;
    private ParticleSystem.TrailModule _trail;
    private ParticleSystemRenderer _renderer;
    
    

    [OnValueChanged("UpdateCircle")] public float radius = 1f;
    [OnValueChanged("UpdateCircle")] public float thickness = 0.25f;
    [OnValueChanged("UpdateMaterial")] public Material material;

    [OnValueChanged("UpdateCircle")] public Vector3 orbitSpeed = new Vector3(0, 0, 0.1f);

    [OnValueChanged("UpdateCircle")] public bool isSolid = false;
    


    private void Awake() {
        _particleSystem = GetComponent<ParticleSystem>();
        
        _main = _particleSystem.main;
        _shape = _particleSystem.shape;
        _emission = _particleSystem.emission;
        _velocity = _particleSystem.velocityOverLifetime;
        _renderer = GetComponent<ParticleSystemRenderer>();

    }

    private void Start() {
        UpdateMaterial();        
        UpdateCircle();
    }

    void UpdateCircle() {
        
        if(Application.isEditor) {
            _particleSystem = GetComponent<ParticleSystem>();
            _main = _particleSystem.main;
            _shape = _particleSystem.shape;
            _emission = _particleSystem.emission;
            _velocity = _particleSystem.velocityOverLifetime;
            _trail = _particleSystem.trails;

        }
        
        SetMain();
        SetEmission();
        SetVelocity();
        SetShape();
        SetTrail();
        
        _particleSystem.Stop();
        _particleSystem.Play();

    }

    void UpdateMaterial() {
        if(Application.isEditor)
            _renderer = GetComponent<ParticleSystemRenderer>();
        
        _renderer.material = material;
        _renderer.trailMaterial = material;
    }

    void SetMain() {
        
        _main.startLifetime = Mathf.Infinity;
        _main.prewarm = true;
        _main.loop = true;
        
        float perimeter = 2 * Mathf.PI * radius;
        _main.maxParticles = Mathf.CeilToInt(perimeter);
        _main.startSize = thickness;
    }

    void SetEmission() {
        _emission.rateOverTime = _main.maxParticles;
    }

    void SetVelocity() {
        _velocity.orbitalX = orbitSpeed.x;
        _velocity.orbitalY = orbitSpeed.y;
        _velocity.orbitalZ = orbitSpeed.z;
    }

    void SetShape() {
        _shape.arc = 360;
        _shape.arcMode = ParticleSystemShapeMultiModeValue.BurstSpread;
        _shape.arcSpread = 0;
        _shape.radius = radius;
    }

    void SetTrail() {
        _trail.enabled = isSolid;

        if (isSolid)
            _renderer.trailMaterial = material;
    }
    
    
}

Uses Odin for some editor functionality, which can be stripped if you don't have it in your project.