BabylonJS - saving particles

HTML

<script src="https://dl.dropboxusercontent.com/u/12395133/babylon.1.12-beta.js"></script>
<div id="rootDiv">
  <button id="btnCreate">Create particles</button>
  <button id="btnRun">Run effect</button>
  <canvas id="canvas"></canvas>
</div>

CSS

html, body, div, canvas {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
    overflow: hidden;
}
#btnRun {
    top: 40px;
}
#btnRun, #btnCreate {
    position:fixed;
    color:#555;
    font-size:11px;
    font-family:courier;
    width:100px;
    height:40px;
}

JavaScript

var canvas = document.getElementById("canvas");
var engine = new BABYLON.Engine(canvas, false);
var scene = new BABYLON.Scene(engine);
var camera = new BABYLON.ArcRotateCamera("Camera", 1, 0.8, 10, new BABYLON.Vector3(0, 0, 0), scene);
camera.setPosition(new BABYLON.Vector3(0, 5, -5));
var light0 = new BABYLON.HemisphericLight("Omni", new BABYLON.Vector3(0, 0, 10), scene);
scene.activeCamera.attachControl(canvas);
engine.runRenderLoop(function () {
    scene.render();
});
var imgSrc = "https://dl.dropboxusercontent.com/u/12395133/babylon/cloud_dot.png";

window.particleSystem = null;
var source = BABYLON.Mesh.CreateBox("source", 0.1, scene);

$("#btnCreate").click(function(){
    if(particleSystem) {
        particleSystem.stop();
    }   
    particleSystem = new BABYLON.ParticleSystem("particles", 5000, scene);
    particleSystem.particleTexture = new BABYLON.Texture(imgSrc, scene);
    particleSystem.emitter = source;
    particleSystem.color1 = new BABYLON.Color4(0, 0, 0, 1.0);
    particleSystem.color2 = new BABYLON.Color4(0.5, 0, 0, 1.0);
    particleSystem.colorDead = new BABYLON.Color4(1, 1, 0, 0.1);
    particleSystem.minSize = 0.1;
    particleSystem.maxSize = 0.2;
    particleSystem.minLifeTime = 0.8;
    particleSystem.maxLifeTime = 0.9;
    particleSystem.emitRate = 2000;
    particleSystem.blendMode = BABYLON.ParticleSystem.BLENDMODE_STANDARD;
    particleSystem.gravity = new BABYLON.Vector3(0, 0, 0);
    particleSystem.direction1 = new BABYLON.Vector3(1, 0, 0);
    particleSystem.direction2 = new BABYLON.Vector3(0, 0, 1);
    particleSystem.minAngularSpeed = 0;
    particleSystem.maxAngularSpeed = 0.1;
    particleSystem.minEmitPower = 2;
    particleSystem.maxEmitPower = 2;   
    particleSystem.minEmitBox = new BABYLON.Vector3(0, 0, 0); 
    particleSystem.maxEmitBox = new BABYLON.Vector3(0, 0, 0);    
    particleSystem.updateSpeed = 0.02;
    particleSystem.targetStopDuration = 7;
   // particleSystem.manualEmitCount = 5000;
   ...