Tween Particle Emitter Speed

class Example extends Phaser.Scene
{
    preload ()
    {
        this.load.setBaseURL('https://cdn.phaserfiles.com/v410');
        this.load.image('bg', 'assets/tweens/sky.png');
        this.load.atlas('match3', 'assets/atlas/match3.png', 'assets/atlas/match3.json');
    }

    create ()
    {
        this.add.image(400, 300, 'bg');

        const emitter = this.add.particles(400, 300, 'match3', {
            frame: 'Match3_Icon_32',
            speed: 20,
            lifespan: 2000,
            scale: 0.3
        });

        this.tweens.add({
            targets: emitter,
            speed: 200,
            duration: 2000,
            yoyo: true,
            repeat: -1
        });
    }
}

const config = {
    scale: { mode: Phaser.Scale.FIT },
    type: Phaser.AUTO,
    width: 800,
    height: 600,
    backgroundColor: '#000',
    parent: 'game-container',
    scene: Example
};

const game = new Phaser.Game(config);